CVE-2023-36811

Name of the Vulnerable Software and Affected Versions borgbackup versions prior to 1.2.5

Description A flaw in the cryptographic authentication scheme in borgbackup allowed an attacker to fake archives and potentially indirectly cause backup data loss in the repository. The attack requires an attacker to be able to: 1. insert files (with no additional headers) into backups and 2. gain write access to the repository. This issue does not disclose plaintext to the attacker, nor does it affect the authenticity of existing archives. Creating plausible fake archives may be feasible for empty or small archives, but is unlikely for large archives.

Recommendations To resolve the issue, upgrade to borgbackup version 1.2.5 or later. Additionally, follow the upgrade procedure as documented in the change log. As a temporary measure to avoid data loss after being attacked, review the archives (timestamp and contents valid and as expected) after any "borg check --repair" and before "borg prune".