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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-85185
StatePUBLISHED
Assignercanonical
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-28 14:17:20 UTC
Updated2026-09-28 17:17:51 UTC
DescriptionPath 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.

Risk And Classification

Primary CVSS: v3.1 9.6 CRITICAL from [email protected]

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

EPSS: 0.003610000 probability, percentile 0.273580000 (date 2026-09-29)

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

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary9.6CRITICALCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:H
3.1CNACVSS9.6CRITICALCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:H

CVSS v3.1 Breakdown

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

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Canonical LXD affected 4.0.2 4.0.14 semver Linux
CNA Canonical LXD affected 5.0.0 5.0.10 semver Linux
CNA Canonical LXD affected 5.21.0 5.21.8 semver Linux
CNA Canonical LXD affected 6.0 6.10 semver Linux

References

ReferenceSourceLinkTags
github.com/canonical/lxd/security/advisories/GHSA-27q7-qwhm-c34p [email protected] github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Additional Advisory Data

Solutions

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

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