CVE-2026-62943

btrbk is a tool for creating snapshots and remote backups of Btrfs subvolumes. From 0.29.0 until 0.32.7, btrbk's ssh_filter_btrbk.sh constructs allow_stream_match with a start anchor but without an end-of-string anchor for the complete command. A user restricted through an authorized_keys forced command can append a trailing pipe command after a valid btrbk command prefix, bypassing the allowlist and executing arbitrary commands with the privileges of the backup-target SSH account. Deployments that do not use ssh_filter_btrbk.sh in authorized_keys are not affected. This issue is fixed in version 0.32.7.

• https://github.com/digint/btrbk/commit/29ca3c093205395bdeb9dd98677ab4139c458aec
• https://github.com/digint/btrbk/releases/tag/v0.32.7
• https://github.com/digint/btrbk/security/advisories/GHSA-pf45-7g54-65h5