Path Traversal in Canonical Lxd
CVE-2026-66897
A path traversal vulnerability in LXD's instance template processing allows an attacker with container edit permissions, or any user launching a crafted image, to overwrite arbitrary files on the host system as root. When processing target template paths specified in metadata.yaml, LXD validates the path against a confined os.Root directory handle but subsequently opens and creates the file using os.Create with an unconfined string path. This discrepancy between path resolution checks and file creation allows an attacker to escape directory confinement, overwrite root-owned host files, and achieve host root code execution.
Vulnerability class: Path Traversal (Directory Traversal)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.9 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.007 (52.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 52nd percentile — 52.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.006 · newest: 0.007 · change: +0.001
Affected products
Weakness classification (CWE)
References
- github.com/canonical/lxd/security/advisories/GHSA-q39m-8fx9-42fv (Exploit, vendor-advisory, vdb-entry, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-66897?
- CVE-2026-66897 is a critical-severity vulnerability in Canonical Lxd, classified under Path Traversal. CVSS score: 9.9/10. Published 2026-08-24.
- How severe is CVE-2026-66897?
- Critical severity. CVSS v3 base score is 9.9 out of 10.