authlib joserfc up to 1.7.3 General JSON Serialization joserfc/jws.py joserfc.jws.deserialize_json improper authentication

Summaryinfo

A vulnerability was found in authlib joserfc up to 1.7.3 and classified as critical. Impacted is the function joserfc.jws.deserialize_json of the file joserfc/jws.py of the component General JSON Serialization. Such manipulation leads to improper authentication. This vulnerability is listed as CVE-2026-102946. The attack may be performed from remote. There is no available exploit. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, has been found in authlib joserfc up to 1.7.3. Affected by this issue is the function joserfc.jws.deserialize_json of the file joserfc/jws.py of the component General JSON Serialization. The manipulation with an unknown input leads to a improper authentication vulnerability. Using CWE to declare the problem leads to CWE-287. When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. Impacted is confidentiality, integrity, and availability. CVE summarizes:

joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. Prior to 1.7.4, joserfc.jws.deserialize_json() accepts a JWS General JSON Serialization with an empty signatures array as authenticated. The verify_general_json() loop performs no iterations for the empty array and returns success because no signature check failed, allowing an attacker without a signing key to supply an arbitrary payload that relying applications may treat as authentic. The issue affects the General JSON Serialization path; compact JWS and JWT decoding, Flattened JSON serialization, and JWE JSON processing do not follow this vulnerable path. This issue is fixed in version 1.7.4.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-102946 since 09/29/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are known technical details, but no exploit is available.

Upgrading to version 1.7.4 eliminates this vulnerability.

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Productinfo

Vendor

• authlib

Name

• joserfc

Version

• 1.7.0
• 1.7.1
• 1.7.2
• 1.7.3

Website

• Product: https://github.com/authlib/joserfc/

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