CVE-2026-25537: keats jsonwebtoken Type Confusion

Vulnerability summary

CVE-2026-25537 is a high (CVSS 7.5) Type Confusion vulnerability in keats jsonwebtoken. EPSS estimates a 0.62% chance of exploitation in the next 30 days, higher than 48.8% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 04-02-2026
   PublishedVulnerability first disclosed.
2. 05-02-2026
   Last modifiedVulnerability information updated.

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.

• CWE-843Access of Resource Using Incompatible Type ('Type Confusion')The product allocates or initializes a resource such as a pointer, object, or variable using one type, but it later accesses that resource using a type that is incompatible with the original type.