{"id":"UBUNTU-CVE-2026-62943","details":"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.","modified":"2026-09-23T23:31:26Z","published":"2026-09-18T17:16:00Z","upstream":["CVE-2026-62943"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-62943"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-62943"},{"type":"REPORT","url":"https://github.com/digint/btrbk/security/advisories/GHSA-pf45-7g54-65h5"},{"type":"REPORT","url":"https://github.com/digint/btrbk/commit/29ca3c093205395bdeb9dd98677ab4139c458aec"},{"type":"REPORT","url":"https://github.com/digint/btrbk/commit/29ca3c093205395bdeb9dd98677ab4139c458aec"},{"type":"REPORT","url":"https://github.com/digint/btrbk/releases/tag/v0.32.7"}],"affected":[{"package":{"name":"btrbk","ecosystem":"Ubuntu:16.04:LTS","purl":"pkg:deb/ubuntu/btrbk?arch=source&distro=xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.19.3-1","0.20.0-1","0.21.0-1","0.22.0-1","0.22.1-1","0.22.2-1"],"ecosystem_specific":{"binaries":[{"binary_name":"btrbk","binary_version":"0.22.2-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-62943.json"}},{"package":{"name":"btrbk","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/btrbk?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.25.1-1","0.26.0-1"],"ecosystem_specific":{"binaries":[{"binary_version":"0.26.0-1","binary_name":"btrbk"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-62943.json"}},{"package":{"name":"btrbk","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/btrbk?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.27.1-1"],"ecosystem_specific":{"binaries":[{"binary_version":"0.27.1-1","binary_name":"btrbk"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-62943.json"}},{"package":{"name":"btrbk","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/btrbk?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.27.1-2","0.31.3-1"],"ecosystem_specific":{"binaries":[{"binary_name":"btrbk","binary_version":"0.31.3-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-62943.json"}},{"package":{"name":"btrbk","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/btrbk?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.32.5-1"],"ecosystem_specific":{"binaries":[{"binary_name":"btrbk","binary_version":"0.32.5-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-62943.json"}},{"package":{"name":"btrbk","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/btrbk?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.32.6-2"],"ecosystem_specific":{"binaries":[{"binary_name":"btrbk","binary_version":"0.32.6-2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-62943.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"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"},{"type":"Ubuntu","score":"medium"}]}