CVE-2023-2975

A vulnerability was found in OpenSSL. The AES-SIV cipher implementation contains a bug that causes it to ignore empty associated data entries, which are unauthenticated as a consequence. Applications that use the AES-SIV algorithm and want to authenticate empty data entries as associated data can be misled by removing, adding, or reordering such empty entries as these are ignored by the OpenSSL implementation. The AES-SIV algorithm allows for the authentication of multiple associated data entries and encryption. To authenticate empty data, the application has to call EVP_EncryptUpdate() (or EVP_CipherUpdate()) with a NULL pointer as the output buffer and 0 as the input buffer length. The AES-SIV implementation in OpenSSL returns success for such a call instead of performing the associated data authentication operation. Thus, the empty data will not be authenticated.