CVE-2026-93853

Summary

Unverified ownership in Barman snapshot backup deletion allows a principal who can write the backup catalog to cause Barman to delete unrelated cloud snapshots. When a snapshot backup is deleted, either explicitly or by retention policy enforcement, Barman reads the snapshot identifiers from the backup.info file and passes them to the cloud provider's delete API using Barman's own credentials, without verifying that the snapshots belong to that backup. An attacker who can overwrite backup.info but lacks snapshot delete permissions can substitute the identifiers of other snapshots, causing Barman to delete any snapshot its cloud identity can reach on AWS, Microsoft Azure, or Google Cloud. Exploitation requires a deployment where the principal that writes the backup catalog is separate from the identity Barman uses to delete snapshots. Barman versions from 3.4.0 (Google Cloud), 3.6.0 (Azure), and 3.7.0 (AWS) up to and including 3.20.0 are affected. The issue is fixed in Barman 3.20.1.

Affected Software

Weaknesses

• CWE-283: CWE-283 Unverified Ownership

Workarounds

Restrict write access to the backup catalog in object storage to the identity Barman uses. Enable object versioning or object lock on the backup bucket, and on AWS use EBS Snapshot Lock (aws_snapshot_lock_mode) to protect snapshots from deletion.

References

• https://www.enterprisedb.com/docs/security/advisories/cve202693853/

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