CVE-2026-63295

Canonical LXD contains an authorization bypass (CWE-863) in its enforcement of project-level container privilege restrictions. When a LXD project is configured to restrict container privileges — for example with restricted.containers.privilege=isolated — the requirement is not enforced if an instance's configuration omits the security.idmap.isolated key, so an authenticated user can create or update an instance without setting that key and sidestep the project's security constraints. Successful exploitation lets an authenticated, low-privileged LXD user run containers with more privilege than the project's isolation policy intends, weakening tenant separation on shared LXD hosts; the CVSS 4.3 (medium) score reflects a network vector, low privileges required, and only a low availability impact. Only deployments using restricted projects with privilege isolation (typically multi-tenant or shared LXD servers) are directly affected, while single-administrator installs are largely unaffected. As of this analysis there are no reports of in-the-wild exploitation (EPSS 0.2%, not in CISA KEV), and a vendor advisory is available at GHSA-7vp9-3vmp-c5jm.

What to do: Update LXD to the fixed release identified in Canonical's advisory (GHSA-7vp9-3vmp-c5jm); no specific version numbers are provided in this data. In the meantime, audit LXD projects configured with restricted.containers.privilege=isolated and ensure instance definitions explicitly set security.idmap.isolated so the restriction cannot be silently bypassed. Restrict who can create or update instances in restricted projects to trusted users until patched.