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| Source | ID | Title |
|---|---|---|
Github GHSA |
GHSA-ww5h-9m49-7xx4 | fast-jwt: Incomplete patch of CVE-2026-34950: Non-whitespace key-prefix re-enables RSA→HS256 algorithm confusion |
Thu, 08 Oct 2026 22:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | fast-jwt provides fast JSON Web Token (JWT) implementation. From 6.2.0 until 6.3.0, fast-jwt can misclassify RSA public-key text as an HMAC secret when the key has non-whitespace content before its PEM header. In src/crypto.js, performDetectPublicKeyAlgorithms trims whitespace but publicKeyPemMatcher remains start-anchored, so comments, control characters, zero-width characters, or wrapper text can prevent PEM detection and reach the HMAC fallback. An attacker who knows the public key bytes can sign arbitrary HS256 claims with that public material when HS256 is inferred or allowed, resulting in authentication or authorization bypass. An asymmetric-only algorithm allowlist prevents the attack. This issue is fixed in version 6.3.0. | |
| Title | fast-jwt: Incomplete patch of CVE-2026-34950: Non-whitespace key-prefix re-enables RSA→HS256 algorithm confusion | |
| Weaknesses | CWE-347 | |
| References |
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| Metrics |
cvssV3_1
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Subscriptions
No data.
Status: PUBLISHED
Assigner: GitHub_M
Published:
Updated: 2026-10-08T21:49:55.888Z
Reserved: 2026-10-08T17:21:52.975Z
Link: CVE-2026-107722
No data.
Status : Deferred
Published: 2026-10-08T22:17:28.447
Modified: 2026-10-08T22:17:28.583
Link: CVE-2026-107722
No data.
OpenCVE Enrichment
No data.
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CWE-347
Improper Verification of Cryptographic Signature
Github GHSA