CVE-2026-85526
Path traversal via Btrfs optimized-backup subvolumes[].path enables root file/dir manipulation in LXD
- 9.9CriticalCVSS base score
- 0.53%Exploitation in 30 daysEPSS · top 55% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- YesPublic exploitsa reference or SSVC says so
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.
Public exploit
An exploit or proof of concept is public: anyone can try it against an unpatched system. CISA's SSVC rates its exploitation: a proof of concept is public.
Timeline
ID reserved
By canonical
- 24 days later
· 24 days later
Published
- 1 day later
· 1 day later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| canonicalCNA (assigner) | 3.1 | Critical9.9 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H |
| NVDNVD · Deferred | 3.1 | Critical9.9 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 0.53% · top 55% of all CVEs (11 Nov 2026)
- CISA SSVC
- Exploitation: poc · Automatable: no · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: Critical 9.9.
Affected products
What to do
Solution: Upgrade to LXD versions 4.0.14, 5.0.10, 5.21.8, 6.10 or later.
References
References6
- https://github.com/canonical/lxd/security/advisories/GHSA-h85r-gjgx-g2rv (opens in a new tab)vendor-advisoryissue-tracking
- https://github.com/canonical/lxd-private/pull/87 (opens in a new tab)patch
- https://github.com/canonical/lxd-private/pull/105 (opens in a new tab)patch
- https://github.com/canonical/lxd-private/pull/104 (opens in a new tab)patch
- https://github.com/canonical/lxd-private/pull/103 (opens in a new tab)patch
- https://github.com/canonical/lxd-private/pull/84 (opens in a new tab)patch
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-88257 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-85526)Record last updated .