Authorization bypass via TOCTOU in LXD cross-project instance copy (CVE-2026-63297)

When copying an instance across projects in LXD, the target project restriction check runs before source instance configuration is merged into the request. This allows an authenticated attacker with view access to a source instance and create access in a restricted target project to copy instances carrying dangerous configuration keys (such as security.privileged, raw.lxc, raw.apparmor) into the restricted project, bypassing all project-level security controls. Successful exploitation can lead to a privileged container being created in a restricted project, enabling a full host escape. Affected versions: - >= 5.0.0, < 6.9 We recommend updating to: 5.0.8, 5.21.6. CVSS 9.9 · our assessment: act_now Reference: https://github.com/canonical/lxd/security/advisories/GHSA-v989-qw7w-xvg4 Details: https://vuln.today/cve/CVE-2026-63297