Paper/Archive/CVE-2026-63297

CVE-2026-63297

Canonical LXD — Cross-project instance copy bypasses target project restrictions via TOCTOU in config merge

Description · from the CVE record

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.

Affected

ProductAffectedFixed inSource
LXD5.0.0 – < 5.0.85.0.8CNA
LXD5.21.0 – < 5.21.65.21.6CNA

Scores by source

canonical (CNA)9.9CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
CISA ADPSSVCExploitation: poc · Automatable: no · Technical impact: total

References

exploitgithub.com/canonical/lxd/security/advisories/GHSA-v989-qw7w-xvg4