Medium severity4.2NVD Advisory· Published Apr 9, 2026· Updated Apr 14, 2026
CVE-2026-35041
CVE-2026-35041
Description
fast-jwt provides fast JSON Web Token (JWT) implementation. From 5.0.0 to 6.2.0, a denial-of-service condition exists in fast-jwt when the allowedAud verification option is configured using a regular expression. Because the aud claim is attacker-controlled and the library evaluates it against the supplied RegExp, a crafted JWT can trigger catastrophic backtracking in the JavaScript regex engine, resulting in significant CPU consumption during verification. This vulnerability is fixed in 6.2.1.
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Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
fast-jwtnpm | >= 5.0.0, < 6.2.1 | 6.2.1 |
Affected products
2Patches
Vulnerability mechanics
References
6- github.com/nearform/fast-jwt/commit/b0be0ca161593836a153d5180ca5358ad9b5de94nvdPatchWEB
- github.com/nearform/fast-jwt/pull/595nvdIssue TrackingPatchWEB
- github.com/nearform/fast-jwt/security/advisories/GHSA-cjw9-ghj4-fwxfnvdExploitMitigationVendor AdvisoryWEB
- github.com/advisories/GHSA-cjw9-ghj4-fwxfghsaADVISORY
- nvd.nist.gov/vuln/detail/CVE-2026-35041ghsaADVISORY
- github.com/nearform/fast-jwt/releases/tag/v6.2.1nvdProductRelease NotesWEB
News mentions
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