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GET /api/packages/1029210?format=api
{ "url": "http://public2.vulnerablecode.io/api/packages/1029210?format=api", "purl": "pkg:npm/%40node-oauth/oauth2-server@5.0.0-rc.5", "type": "npm", "namespace": "@node-oauth", "name": "oauth2-server", "version": "5.0.0-rc.5", "qualifiers": {}, "subpath": "", "is_vulnerable": true, "next_non_vulnerable_version": "5.3.0", "latest_non_vulnerable_version": "5.3.0", "affected_by_vulnerabilities": [ { "url": "http://public2.vulnerablecode.io/api/vulnerabilities/90130?format=api", "vulnerability_id": "VCID-3f8w-76vg-sfdr", "summary": "@node-oauth/oauth2-server: PKCE code_verifier ABNF not enforced in token exchange allows brute-force redemption of intercepted authorization codes\n## Summary\n\nThe token exchange path accepts RFC7636-invalid `code_verifier` values (including one-character strings) for `S256` PKCE flows. \nBecause short/weak verifiers are accepted and failed verifier attempts do not consume the authorization code, an attacker who intercepts an authorization code can brute-force `code_verifier` guesses online until token issuance succeeds.\n\n\n\n### Root cause\n\n1. `lib/pkce/pkce.js` (`getHashForCodeChallenge`) only checks that `verifier` is a non-empty string before hashing for `S256`; it does not enforce RFC7636 ABNF (`43..128` unreserved chars).\n2. `lib/grant-types/authorization-code-grant-type.js` compares `hash(code_verifier)` to stored `codeChallenge` without validating verifier format/length.\n3. In `AuthorizationCodeGrantType.handle`, authorization code revocation happens **after** verifier validation. Invalid guesses fail before revoke, so the same code can be retried repeatedly.\n\n## Steps to Reproduce\n\n### Setup\n\n- PKCE authorization code exists with:\n - `codeChallengeMethod = \"S256\"`\n - `codeChallenge = BASE64URL(SHA256(\"z\"))` (verifier is one character, RFC-invalid)\n- Attacker has intercepted the authorization code value.\n\n### Reproduction\n\n1. Send repeated token requests with guessed `code_verifier` values:\n\n```http\nPOST /token HTTP/1.1\nHost: oauth.example\nContent-Type: application/x-www-form-urlencoded\n\ngrant_type=authorization_code&\nclient_id=client1&\nclient_secret=s3cret&\ncode=stolen-auth-code&\nredirect_uri=https://client.example/callback&\ncode_verifier=<guess>\n```\n\n2. Observe invalid guesses return `invalid_grant`.\n3. Continue guessing (`a`..`z`).\n4. When `code_verifier=z`, token issuance succeeds and returns bearer tokens.\n\n### Confirmed PoC output\n\n```text\nBRUTE_FORCE_SUCCESS { tries: 26, guess: 'z', status: 200, tokenIssued: true }\n```\n\n## Impact\n\nAn intercepted authorization code can be redeemed by brute-forcing low-entropy verifiers that the server should have rejected under RFC7636. \nThis weakens PKCE’s protection goal and allows token theft when clients generate short/predictable verifiers.\n\n## Recommended Fix\n\n1. Enforce `pkce.codeChallengeMatchesABNF(request.body.code_verifier)` in authorization code token exchange before hashing/comparison.\n2. Reject verifier values outside RFC7636 charset/length (`43..128` unreserved).\n3. Invalidate authorization codes on failed verifier attempts (or add strict retry limits) to prevent online guessing.", "references": [ { "reference_url": "https://api.first.org/data/v1/epss?cve=CVE-2026-41213", "reference_id": "", "reference_type": "", "scores": [ { "value": "0.00158", "scoring_system": "epss", "scoring_elements": "0.36528", "published_at": "2026-06-06T12:55:00Z" }, { "value": "0.00158", "scoring_system": "epss", "scoring_elements": "0.36455", "published_at": "2026-06-08T12:55:00Z" }, { "value": "0.00158", "scoring_system": "epss", "scoring_elements": "0.36491", "published_at": "2026-06-07T12:55:00Z" }, { "value": "0.00158", "scoring_system": "epss", "scoring_elements": "0.36519", "published_at": "2026-06-05T12:55:00Z" } ], "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-41213" }, { "reference_url": "https://github.com/node-oauth/node-oauth2-server", "reference_id": "", "reference_type": "", "scores": [ { "value": "5.9", "scoring_system": "cvssv3.1", "scoring_elements": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N" }, { "value": "MODERATE", "scoring_system": "generic_textual", "scoring_elements": "" } ], "url": "https://github.com/node-oauth/node-oauth2-server" }, { "reference_url": "https://github.com/node-oauth/node-oauth2-server/security/advisories/GHSA-jhm7-29pj-4xvf", "reference_id": "", "reference_type": "", "scores": [ { "value": "5.9", "scoring_system": "cvssv3.1", "scoring_elements": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N" }, { "value": "MODERATE", "scoring_system": "cvssv3.1_qr", "scoring_elements": "" }, { "value": "MODERATE", "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/2026-04-25T01:23:23Z/" } ], "url": "https://github.com/node-oauth/node-oauth2-server/security/advisories/GHSA-jhm7-29pj-4xvf" }, { "reference_url": "https://nvd.nist.gov/vuln/detail/CVE-2026-41213", "reference_id": "", "reference_type": "", "scores": [ { "value": "5.9", "scoring_system": "cvssv3.1", "scoring_elements": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N" }, { "value": "MODERATE", "scoring_system": "generic_textual", "scoring_elements": "" } ], "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-41213" }, { "reference_url": "https://github.com/advisories/GHSA-jhm7-29pj-4xvf", "reference_id": "GHSA-jhm7-29pj-4xvf", "reference_type": "", "scores": [ { "value": "MODERATE", "scoring_system": "cvssv3.1_qr", "scoring_elements": "" } ], "url": "https://github.com/advisories/GHSA-jhm7-29pj-4xvf" } ], "fixed_packages": [ { "url": "http://public2.vulnerablecode.io/api/packages/111392?format=api", "purl": "pkg:npm/%40node-oauth/oauth2-server@5.3.0", "is_vulnerable": false, "affected_by_vulnerabilities": [], "resource_url": "http://public2.vulnerablecode.io/packages/pkg:npm/%2540node-oauth/oauth2-server@5.3.0" } ], "aliases": [ "CVE-2026-41213", "GHSA-jhm7-29pj-4xvf" ], "risk_score": 3.1, "exploitability": "0.5", "weighted_severity": "6.2", "resource_url": "http://public2.vulnerablecode.io/vulnerabilities/VCID-3f8w-76vg-sfdr" } ], "fixing_vulnerabilities": [], "risk_score": "3.1", "resource_url": "http://public2.vulnerablecode.io/packages/pkg:npm/%2540node-oauth/oauth2-server@5.0.0-rc.5" }