CVE-2026-107719: CWE-613: Insufficient Session Expiration in nearform fast-jwt
Description
fast-jwt versions prior to 6.3.4 have an insufficient session expiration vulnerability where cached JWTs with an exp claim but no iat claim can be accepted beyond their expiration time when caching is enabled. This allows replay of previously valid tokens until the cache entry expires. The issue is fixed in version 6.3.4.
CVSS v3.1
Score 4.2medium
Affected software
nearform
fast-jwt
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The fast-jwt library's createVerifier cache mechanism incorrectly handles JWT expiration when tokens have an exp claim but lack an iat claim. Specifically, the cache expiration deadline is derived only if the iat claim is present; otherwise, the cache falls back to a default TTL. This allows the cache to return a previously valid token payload after the token's exp time without rechecking expiration, enabling replay of expired tokens until the cache entry expires. This vulnerability does not allow token forgery. The issue is resolved in fast-jwt version 6.3.4.
Potential Impact
An attacker able to replay a cached bearer token can extend access beyond the token's expiration time until the cache entry expires. This could lead to unauthorized prolonged access using expired tokens. However, the vulnerability does not permit forging tokens or elevating privileges beyond the token's original scope.
Mitigation Recommendations
Upgrade fast-jwt to version 6.3.4 or later, where this issue is fixed. No other mitigation is required as the fix addresses the root cause.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-10-08T17:21:52.975Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6ac8135e2cdf04f6563b0ceb
Added to database: 10/08/2026, 22:04:14 UTC
Last enriched: 10/08/2026, 22:18:54 UTC
Last updated: 10/08/2026, 22:19:11 UTC
Views: 7
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