CVE-2026-62943 btrbk: SSH Command Filter Bypass in ssh_filter_btrbk.sh
Attackers with restricted SSH access can bypass command filters in btrbk to execute arbitrary commands on the backup target system.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-62943?
CVE-2026-62943 is a high-severity command injection vulnerability in digint btrbk, published on 18 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
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.
Weakness: CWE-78
Which versions are affected by CVE-2026-62943?
How do I fix CVE-2026-62943?
No fix has been published for CVE-2026-62943 yet. Limit exposure of the affected software until one is available.
Upgrade, and pass arguments to programs as a list instead of through a shell. More about Command injection.
Is CVE-2026-62943 being exploited?
There is no known exploitation of CVE-2026-62943 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-62943, GHSA-pf45-7g54-65h5, UBUNTU-CVE-2026-62943.