Answer in brief
CVE-2026-107722 records a Critical severity (CVSS 9.8) vulnerability in fast-jwt: Incomplete patch of CVE-2026-34950: Non-whitespace key-prefix re-enables RSA→HS256 algorithm confusion. The current sources do not mark it as known exploited. The current feed maps nearform/fast-jwt (generic), fast-jwt (npm), fast-jwt (npm). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 9.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps nearform/fast-jwt (generic), fast-jwt (npm), fast-jwt (npm). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| nearform/fast-jwtgeneric | >=6.2.0 <6.3.0 | 6.3.0 |
| fast-jwtnpm | >=6.2.0,<=6.2.4 | 6.3.0 |
| fast-jwtnpm | >=6.2.0 <6.3.0 | 6.3.0 |
Published upstream
Oct 8, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 8, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Oct 8, 2026
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.
Quoted source text, attributed separately from HOL analysis.