UBUNTU-CVE-2026-62943 (CVE-2026-62943)

Vulnerability from osv_ubuntu – Published: 2026-09-21 00:00 – Updated: 2026-09-21 00:00 – Source website
VLAI
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.

Severity
8.7 (High)
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
N/A (UNKNOWN)
medium
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "btrbk",
            "binary_version": "0.22.2-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:16.04:LTS",
        "name": "btrbk",
        "purl": "pkg:deb/ubuntu/btrbk@0.22.2-1?arch=source\u0026distro=xenial"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "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": "0.26.0-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:18.04:LTS",
        "name": "btrbk",
        "purl": "pkg:deb/ubuntu/btrbk@0.26.0-1?arch=source\u0026distro=bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.25.1-1",
        "0.26.0-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "btrbk",
            "binary_version": "0.27.1-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:20.04:LTS",
        "name": "btrbk",
        "purl": "pkg:deb/ubuntu/btrbk@0.27.1-1?arch=source\u0026distro=focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.27.1-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "btrbk",
            "binary_version": "0.31.3-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "btrbk",
        "purl": "pkg:deb/ubuntu/btrbk@0.31.3-1?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.27.1-2",
        "0.31.3-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "btrbk",
            "binary_version": "0.32.5-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "btrbk",
        "purl": "pkg:deb/ubuntu/btrbk@0.32.5-1?arch=source\u0026distro=noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.32.5-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "btrbk",
            "binary_version": "0.32.6-2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "btrbk",
        "purl": "pkg:deb/ubuntu/btrbk@0.32.6-2?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.32.6-2"
      ]
    }
  ],
  "aliases": [],
  "details": "btrbk is a tool for creating snapshots and remote backups of Btrfs subvolumes. From 0.29.0 until 0.32.7, btrbk\u0027s 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.",
  "id": "UBUNTU-CVE-2026-62943",
  "modified": "2026-09-21T00:00:00Z",
  "published": "2026-09-21T00:00:00Z",
  "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"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "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": "CVSS_V4"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-62943"
  ]
}



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