Vulnerability Description
jsonwebtoken is a JWT lib in rust. Prior to version 10.3.0, there is a Type Confusion vulnerability in jsonwebtoken, specifically, in its claim validation logic. When a standard claim (such as nbf or exp) is provided with an incorrect JSON type (Like a String instead of a Number), the library’s internal parsing mechanism marks the claim as “FailedToParse”. Crucially, the validation logic treats this “FailedToParse” state identically to “NotPresent”. This means that if a check is enabled (like: validate_nbf = true), but the claim is not explicitly marked as required in required_spec_claims, the library will skip the validation check entirely for the malformed claim, treating it as if it were not there. This allows attackers to bypass critical time-based security restrictions (like “Not Before” checks) and commit potential authentication and authorization bypasses. This issue has been patched in version 10.3.0.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Keats | Jsonwebtoken | < 10.3.0 |
Related Weaknesses (CWE)
References
- https://github.com/Keats/jsonwebtoken/commit/abbc3076742c4161347bc6b8bf4aa5eb86ePatch
- https://github.com/Keats/jsonwebtoken/security/advisories/GHSA-h395-gr6q-cpjcExploitVendor Advisory
- https://github.com/Keats/jsonwebtoken/security/advisories/GHSA-h395-gr6q-cpjcExploitVendor Advisory
FAQ
What is CVE-2026-25537?
CVE-2026-25537 is a vulnerability with a CVSS score of 7.5 (HIGH). jsonwebtoken is a JWT lib in rust. Prior to version 10.3.0, there is a Type Confusion vulnerability in jsonwebtoken, specifically, in its claim validation logic. When a standard claim (such as nbf or ...
How severe is CVE-2026-25537?
CVE-2026-25537 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-25537?
Check the references section above for vendor advisories and patch information. Affected products include: Keats Jsonwebtoken.