CVE-2023-36811
MediumCVSS 4.7Exploitation Probability (EPSS)
Low risk1th percentile - higher than 1% of all known CVEs
Summary
In borgbackup, an open-source deduplicating archiver, a flaw in the cryptographic authentication scheme allowed an attacker to fake archives, potentially leading to backup data loss. The attack required access to the repository and the ability to insert files into backups.
Risk Assessment
Organizations may experience data loss in the backup repository if an attacker gains access to the system and exploits this vulnerability. While the vulnerability does not disclose plaintext data, fake archives could mislead administrators.
Recommendation
It is recommended to upgrade to borgbackup version 1.2.5 and follow the upgrade procedure documented in the change log. After any 'borg check --repair', archives should be thoroughly reviewed before executing 'borg prune'.
Original NVD description (English source)
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.