A high risk vulnerability was found in cjose. The cjose is a C library implementing the Javascript Object Signing and Encryption (JOSE) on which mod_auth_openidc depends. The AES GCM decryption routine incorrectly uses the tag length from the actual Authentication Tag provided in the JSON Web Encryption (JWE). A fixed length of 16 octets must be applied. This flaw allows an attacker to provide a truncated Authentication Tag and modify the JWE. This may allow an attacker to adjust the content of encrypted JSONs.

Details on this vulnerabilities and suggested actions to mitigate it, are available in this SVG Advisory.