Back to CVE List CVE-2026-25537 MEDIUM SEVERITY CVSS Score & Metrics Base Score 7.5 / 10 Vector String CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N 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. Vulnerability Details Published Date February 03, 2026 Last Modified February 11, 2026 CWE ID CWE-843 Source GitHub Vendor rust Product jsonwebtoken External References https://github.com/Keats/jsonwebtoken/security/advisories/GHSA-h395-gr6q-cpjc https://github.com/Keats/jsonwebtoken/commit/abbc3076742c4161347bc6b8bf4aa5eb86e1dc01 https://github.com/advisories/GHSA-h395-gr6q-cpjc