What’s Vulnerable › Vulnerabilities

CVE-2026-85526: Path traversal via Btrfs optimized-backup subvolumes[].path enables root file/dir manipulation in LXD

• Severity: critical (CVSS 9.9 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-28 · updated 2026-09-29
• Weakness: CWE-22

Description

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.

Affected products

• Canonical LXD: from 4.0.0 before 4.0.14; from 5.0.0 before 5.0.10; from 5.21.0 before 5.21.8; from 6.0 before 6.10 — fixed in 4.0.14, 5.0.10, 5.21.8, 6.10

How to fix

Upgrade to a fixed version: Canonical LXD 4.0.14, 5.0.10, 5.21.8, 6.10. Check the vendor advisory for mitigations.

References

• https://github.com/canonical/lxd-private/pull/103
• https://github.com/canonical/lxd-private/pull/104
• https://github.com/canonical/lxd-private/pull/105
• https://github.com/canonical/lxd-private/pull/84
• https://github.com/canonical/lxd-private/pull/87
• https://github.com/canonical/lxd/security/advisories/GHSA-h85r-gjgx-g2rv

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