CVE-2026-85185

critical

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.

References

https://github.com/canonical/lxd/security/advisories/GHSA-27q7-qwhm-c34p

Details

Source: Mitre, NVD

Published: 2026-09-28

Updated: 2026-09-28

Risk Information

CVSS v2

Base Score: 8.5

Vector: CVSS2#AV:N/AC:L/Au:S/C:N/I:C/A:C

Severity: High

CVSS v3

Base Score: 9.6

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

Severity: Critical

EPSS

EPSS: 0.00361