CVE-2026-107721

fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to 6.3.0, fast-jwt createVerifier accepts Infinity for clockTolerance because its option validation checks type and negativity but not finiteness. In validateClaimDateValue, infinite positive and negative modifiers make exp and nbf comparisons always pass, allowing expired or not-yet-active tokens to be accepted. The verifier cache also derives infinite bounds, so entries created under this configuration can remain valid until eviction. Exploitation requires an application administrator or equivalent configuration path to set clockTolerance to Infinity. This issue is fixed in version 6.3.0.

CVSS 3.1

5.9CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:N

EPSS

0.3% chance of exploitation in the next 30 days; higher than 27% of CVEs (scores of 2026-10-25)

CWEs

CWE-613, CWE-682

Published

2026-10-08

Modified

2026-10-09

Record from

the NVD, synced 2026-10-19

Packages (OSV)

References

• https://github.com/nearform/fast-jwt/commit/c0fb5b88b4c88ff2bdd194ca2c713599ad9e38b6
• https://github.com/nearform/fast-jwt/releases/tag/v6.3.0
• https://github.com/nearform/fast-jwt/security/advisories/GHSA-687g-22h4-j4w4

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