CVE-2026-85526

Path traversal via Btrfs optimized-backup subvolumes[].path enables root file/dir manipulation in LXD

State: Published
Severity: 9.9 Critical
Published: Sep 28, 2026
Updated: Sep 29, 2026
Reserved: Sep 4, 2026

Description

Path traversal in the Btrfs storage driver (unpackVolume) in Canonical LXD on Linux allows an authenticated user with instance creation privileges to delete or replace arbitrary files and directories on the host filesystem as root via a crafted subvolumes[].path entry in backup/optimized_header.yaml during a btrfs optimized backup import.

Scores

CVSS	Score	Vector	Source
3.1	9.9 Critical	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H	canonical

Weaknesses

CWE-22 Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Affected Products

Product	Versions
LXDCanonical	4.0.0 to before 4.0.14Affected 5.0.0 to before 5.0.10Affected 5.21.0 to before 5.21.8Affected 6.0 to before 6.10Affected

References

https://github.com/canonical/lxd/security/advisories/GHSA-h85r-gjgx-g2rvvendor-advisoryissue-tracking
https://github.com/canonical/lxd-private/pull/87patch
https://github.com/canonical/lxd-private/pull/105patch
https://github.com/canonical/lxd-private/pull/104patch
https://github.com/canonical/lxd-private/pull/103patch
https://github.com/canonical/lxd-private/pull/84patch

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