CVE-2026-85185

Path traversal in LXD btrfs storage driver allows arbitrary file deletion and write on host as root

Published Sep 28, 2026 CVSS 3.1 · 9.6 Critical EPSS < 1% KEV · Not listed
Description
Path traversal in the btrfs storage driver in Canonical LXD versions 4.0.2 and later (fixed in 4.0.14, 5.0.10, 5.21.8 and 6.10) on Linux allows an authenticated client with permission to create instances in a project to delete arbitrary files on the host as root. On hosts whose root filesystem is btrfs, the client can also place attacker-controlled content at arbitrary host paths, leading to full host compromise. The client does this with a crafted subvolume path containing ../ sequences, sent in either of two ways: in the optimized_header.yaml of an optimized btrfs backup, or in the btrfs migration header sent by a malicious migration source.

Remediation

Vendor Solution

Upgrade to LXD versions 4.0.14, 5.0.10, 5.21.8, 6.10 or later.

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Canonical
Canonical lxd
Vendors & Products Canonical
Canonical lxd
Type Values Removed Values Added
Description Path traversal in the btrfs storage driver in Canonical LXD versions 4.0.2 and later (fixed in 4.0.14, 5.0.10, 5.21.8 and 6.10) on Linux allows an authenticated client with permission to create instances in a project to delete arbitrary files on the host as root. On hosts whose root filesystem is btrfs, the client can also place attacker-controlled content at arbitrary host paths, leading to full host compromise. The client does this with a crafted subvolume path containing ../ sequences, sent in either of two ways: in the optimized_header.yaml of an optimized btrfs backup, or in the btrfs migration header sent by a malicious migration source.
Title Path traversal in LXD btrfs storage driver allows arbitrary file deletion and write on host as root
Weaknesses CWE-22
References
Metrics cvssV3_1

{'score': 9.6, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
canonical
Published
Updated
Sep 28, 2026, 4:32 PM
Reserved
Sep 3, 2026, 11:46 AM
Status
Deferred
Published
Sep 28, 2026, 2:17 PM
Modified
Sep 28, 2026, 5:17 PM