CVE-2026-1077229.8CriticalCWE-347

CVE-2026-107722: fast-jwt: Incomplete patch of CVE-2026-34950: Non-whitespace key-prefix re-enables RSA→HS256 algorithm confusion

nearform · fast-jwt

Affected: nearform fast-jwt · Exploitation: unlikely (under 1%)

Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.

0.4%probability of exploitation in the next 30 days

29th percentile

050100

Higher than 29% of scored CVEs

9.8CriticalCVSS 3.1

LowMediumHighCrit.

DescriptionCVE.org

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.

Affected products1

From the CVE record. A product or version that is not listed is unknown, not unaffected.

nearform · fast-jwt>= 6.2.0, < 6.3.0

On the Atlas

Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.

Open the Atlas

Exploitation: Unlikely (under 1%). EPSS under 1%, or no score yet.
CISA KEV: Not listed
Public check: No public nuclei template
Weakness: Improper Verification of Cryptographic Signature · Cryptography
Vendor: nearform
Published: October 2026
Band: Unlikely (under 1%), October 2026

CoverageNo articles yet

No CyberSIXT article names CVE-2026-107722 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.