Threat Intelligence Database

CVE-2026-53939 is a critical vulnerability in the OpenIDC cjose C library affecting versions 0.6.1 through 0.6.2.5. The flaw causes the content-encryption key (CEK) used in AES-CBC-HMAC encryption to be all zero bytes instead of randomly generated, resulting in encryption under a fixed, publicly known key. This allows anyone with access to the encrypted data to decrypt and modify it. The issue is fixed in version 0.6.2.6. Mitigations for new ciphertexts include using AES-GCM encryption, supplying a CEK directly, or avoiding the affected algorithm combinations. Data already encrypted with the zero key remains compromised and should be re-encrypted with rotated secrets.

OpenIDC/cjose is a C library implementing the Javascript Object Signing and Encryption (JOSE). Prior to version 0.6.2.5, cjose's JWE decryption path for the AES Key Wrap key-management algorithms (`alg` = `A128KW`, `A192KW`, `A256KW`) does not validate the length of the attacker-supplied `encrypted_key` (JWE Encrypted Key) before unwrapping it into a fixed-size, heap-allocated Content Encryption Key (CEK) buffer. A remote, unauthenticated attacker who can submit a crafted JWE to an application that decrypts it with an AES-KW symmetric key can trigger an out-of-bounds heap write, corrupting the heap. This leads at minimum to a crash (denial of service) and, depending on the heap layout and allocator, may be leverageable for further memory-corruption impact. `cjose_jwe_import()` / `cjose_jwe_decrypt()` are pre-authentication entry points: they parse and process fully attacker-controlled input. Upgrade to cjose 0.6.2.5 to receive a patch. If upgrading is not immediately possible, reject the AES Key Wrap algorithms (`A128KW`/`A192KW`/`A256KW`) for untrusted JWEs at the application layer.