Auth bypass in Canonical Lxd
CVE-2026-63297
An authorization bypass vulnerability in LXD due to a timing flaw during configuration merging allows an authenticated attacker to bypass target project restrictions during cross-project instance copies. When copying an instance to a target project, LXD performs restriction checks before configuration merging is complete, creating a time-of-check to time-of-use (TOCTOU) condition. An attacker can exploit this flaw to copy instances with disallowed high-privilege configurations into restricted projects, bypassing security controls.
Vulnerability class: TOCTOU (Time-of-Check to Time-of-Use)
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: 0.003 (25.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 25th percentile — 25.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001
Affected products
- Canonical Lxd — versions 5.0.0, 5.21.0
Weakness classification (CWE)
References
- github.com/canonical/lxd/security/advisories/GHSA-v989-qw7w-xvg4 (Exploit, vendor-advisory, Mitigation, vdb-entry, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-63297?
- CVE-2026-63297 is a critical-severity vulnerability in Canonical Lxd, classified under Time-of-check Time-of-use (TOCTOU) Race Condition. CVSS score: 9.9/10. Published 2026-08-12.
- How severe is CVE-2026-63297?
- Critical severity. CVSS v3 base score is 9.9 out of 10.