Affected: OpenSSL

Issue summary: The AES-SIV cipher implementation contains a bug that causes it to ignore empty associated data entries which are unauthenticated as a consequence.

Impact summary: 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. We are currently unaware of any such applications.

The AES-SIV algorithm allows for authentication of multiple associated data entries along with the encryption. To authenticate empty data the application has to call EVP_EncryptUpdate() (or EVP_CipherUpdate()) with NULL pointer as the output buffer and 0 as the input buffer length. The AES-SIV implementation in OpenSSL just returns success for such a call instead of performing the associated data authentication operation. The empty data thus will not be authenticated.

As this issue does not affect non-empty associated data authentication and we expect it to be rare for an application to use empty associated data entries this is qualified as Low severity issue.

Affected: Ubuntu:22.04:LTS: openssl

Tony Battersby discovered that OpenSSL incorrectly handled key and initialization vector (IV) lengths. This could lead to truncation issues and result in loss of confidentiality for some symmetric cipher modes. (CVE-2023-5363)

Juerg Wullschleger discovered that OpenSSL incorrectly handled the AES-SIV cipher. This could lead to empty data entries being ignored, resulting in certain applications being misled. This issue only affected Ubuntu 22.04 LTS and Ubuntu 23.04. (CVE-2023-2975)

It was discovered that OpenSSL incorrectly handled checking excessively long DH keys or parameters. A remote attacker could possibly use this issue to cause OpenSSL to consume resources, leading to a denial of service. This issue only affected Ubuntu 22.04 LTS and Ubuntu 23.04. (CVE-2023-3446, CVE-2023-3817)