CVE-2026-85526 PUBLISHED

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

Assigner: canonical
Reserved: 04.09.2026 Published: 28.09.2026 Updated: 29.09.2026

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.

Metrics

CVSS 3.1

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

Attack Vector	Network	Scope	Changed
Attack Complexity	Low	Confidentiality Impact	High
Privileges Required	Low	Integrity Impact	High
User Interaction	None	Availability Impact	High

CVSS 3.1

Product Status

Vendor	Canonical
Product	LXD
Versions	Default: unaffected affected from 4.0.0 to 4.0.14 (excl.) affected from 5.0.0 to 5.0.10 (excl.) affected from 5.21.0 to 5.21.8 (excl.) affected from 6.0 to 6.10 (excl.)

Solutions

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

References

Problem Types

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

Impacts

CAPEC-126 Path Traversal