borgbackup is an opensource, deduplicating archiver with compression and authenticated encryption. 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 vulnerability 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. The issue has been fixed in borgbackup 1.2.5. Users are advised to upgrade. Additionally to installing the fixed code, users must follow the upgrade procedure as documented in the change log. Data loss after being attacked can be avoided by reviewing the archives (timestamp and contents valid and as expected) after any "borg check --repair" and before "borg prune". There are no known workarounds for this vulnerability.

The Borg theme before 1.1.19 for Backdrop CMS does not sufficiently sanitize path arguments that are passed in via a URL. The function borg_preprocess_page in the file template.php does not properly sanitize incoming path arguments before using them.

Incorrect implementation of access controls allows remote users to override repository restrictions in Borg servers 1.1.x before 1.1.3.

Borg (aka BorgBackup) before 1.0.9 has a flaw in the cryptographic protocol used to authenticate the manifest (list of archives), potentially allowing an attacker to spoof the list of archives.

Borg (aka BorgBackup) before 1.0.9 has a flaw in the way duplicate archive names were processed during manifest recovery, potentially allowing an attacker to overwrite an archive.