CVE-2026-34950

Summary

fast-jwt provides fast JSON Web Token (JWT) implementation. In 6.1.0 and earlier, the publicKeyPemMatcher regex in fast-jwt/src/crypto.js uses a ^ anchor that is defeated by any leading whitespace in the key string, re-enabling the exact same JWT algorithm confusion attack that CVE-2023-48223 patched.

Affected Software

Weaknesses

• CWE-327: CWE-327: Use of a Broken or Risky Cryptographic Algorithm

ADP Enrichment

CISA ADP Vulnrichment

• SSVC:
• Exploitation: poc
  • Automatable: yes
  • Technical Impact: total

References

• https://github.com/nearform/fast-jwt/security/advisories/GHSA-mvf2-f6gm-w987

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