Vulnerability · Published Sep 28, 2026 · Assigned by canonical
CVE-2026-85185Path traversal in LXD btrfs storage driver allows arbitrary file deletion and write on host as root
Critical 9.6
In plain English
A critical-severity path traversal in LXD from Canonical. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 31% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:13 | incus | 6.0.4-2+deb13u1 | DEBIAN-CVE-2026-85185 |
| Debian:14 | incus | 7.0.1-5 | DEBIAN-CVE-2026-85185 |
| Debian:12 | lxd | no fix listed | DEBIAN-CVE-2026-85185 |
| Debian:13 | lxd | no fix listed | DEBIAN-CVE-2026-85185 |
| Ubuntu:26.10 | incus | no fix listed | UBUNTU-CVE-2026-85185 |
Affected products (as reported)
Weakness: CWE-22 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:H