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Vulnerability · Published Sep 18, 2026 · Assigned by GitHub_M

CVE-2026-62943btrbk: SSH Command Filter Bypass in ssh_filter_btrbk.sh

High 8.7

In plain English

A high-severity OS command injection in btrbk from digint. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 43% of all known vulnerabilities).

Severity (CVSS 4.0)8.7High
Exploit odds (30 days)0.5%top 57.2% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12btrbkno fix listedDEBIAN-CVE-2026-62943
Debian:13btrbkno fix listedDEBIAN-CVE-2026-62943
Debian:14btrbkno fix listedDEBIAN-CVE-2026-62943
Ubuntu:22.04:LTSbtrbkno fix listedUBUNTU-CVE-2026-62943
Ubuntu:24.04:LTSbtrbkno fix listedUBUNTU-CVE-2026-62943
Ubuntu:26.04:LTSbtrbkno fix listedUBUNTU-CVE-2026-62943
Ubuntu:26.10btrbkno fix listedUBUNTU-CVE-2026-62943

Affected products (as reported)

VendorProductVersions
digint btrbk >= 0.29.0, < 0.32.7

Weakness: CWE-78 · 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

References