CVE-2026-62943 Details
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.
A command injection vulnerability has been identified in Btrbk versions 0.29.0 prior to 0.32.7. The issue arises in the 'ssh_filter_btrbk.sh' script, which is used to filter SSH commands. The vulnerability allows users with SSH access to bypass command restrictions and execute arbitrary commands on the server, using the privileges of the SSH user. This exploitation is possible by appending a pipe command to a valid Btrbk command, taking advantage of a regex allowlist that lacked an end-of-string anchor. The vulnerability affects deployments that utilize 'ssh_filter_btrbk.sh' in their authorized_keys file, while those that do not are not impacted.
Users should upgrade to Btrbk version 0.32.7 or later and deploy the updated 'ssh_filter_btrbk.sh' script to all remote backup hosts. For those using 'ssh_filter_btrbk.sh' in their authorized_keys configurations, an immediate upgrade is recommended.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Sep 18, 2026CISA-ADP
Assessed Sep 18, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/digint/btrbk/commit/29ca3c093205395bdeb9dd98677ab4139c458aec | [email protected] | Source CodeVendor |
| https://github.com/digint/btrbk/releases/tag/v0.32.7 | [email protected] | Release NotesVendor |
| https://github.com/digint/btrbk/security/advisories/GHSA-pf45-7g54-65h5 | [email protected] | AdvisoryRemedyVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-78 | Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| btrbk | >= 0.29.0, <= 0.32.6 (semver) |
CPE
Remediation
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Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Sep 21, 2026 | CVE Modified | CISA-ADP |
| Sep 18, 2026 | New CVE Received | [email protected] |