Keats jsonwebtoken up to 10.2.x type confusion

Summaryinfo

A vulnerability described as problematic has been identified in Keats jsonwebtoken up to 10.2.x. Impacted is an unknown function. Such manipulation leads to type confusion. This vulnerability is documented as CVE-2026-25537. The attack can be executed remotely. There is not any exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability was found in Keats jsonwebtoken up to 10.2.x and classified as problematic. Affected by this issue is an unknown code block. The manipulation with an unknown input leads to a type confusion vulnerability. Using CWE to declare the problem leads to CWE-843. 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. Impacted is integrity. CVE summarizes:

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.

The advisory is available at github.com. This vulnerability is handled as CVE-2026-25537 since 02/02/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. The technical details are unknown and an exploit is not available.

The vulnerability scanner Nessus provides a plugin with the ID 298172 (Linux Distros Unpatched Vulnerability : CVE-2026-25537), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 10.3.0 eliminates this vulnerability. Applying the patch abbc3076742c4161347bc6b8bf4aa5eb86e1dc01 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (298172) and EUVD (EUVD-2026-5334). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Vendor

• Keats

Name

• jsonwebtoken

Version

• 10.0
• 10.1
• 10.2

License

• open-source

Website

• Product: https://github.com/Keats/jsonwebtoken/

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If you want to get best quality of vulnerability data, you may have to visit VulDB.

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