CVE-2026-63294

Canonical LXD contains a link-following vulnerability (CWE-59) in its handling of the backup.yaml file during the import or unpacking of image and backup archives: when backup.yaml inside a submitted archive is a symbolic link, LXD follows it without proper confinement and processes unconfined configuration metadata. An attacker who can import a crafted archive — for example an authenticated LXD user or a tenant permitted to load images — can thereby have arbitrary commands executed with root privileges on the host system, breaking container-to-host isolation (CVSS 3.1: 9.9, scope changed). Any LXD deployment that accepts image or backup imports from less-than-fully-trusted users, particularly multi-tenant installations, is affected. Exploitation has not been confirmed in the wild (not listed in CISA KEV; EPSS ~1% over 30 days), but a public proof-of-concept/advisory is available via Canonical's GitHub security advisory GHSA-fv82-v4fj-mm4m.

What to do: Upgrade LXD to the patched release identified in Canonical's security advisory (GHSA-fv82-v4fj-mm4m) and confirm the running version after updating. Until patched, restrict image/backup import permissions to fully trusted administrators and inspect incoming archives, rejecting any where backup.yaml is a symbolic link. Prioritize multi-tenant or internet-reachable LXD instances, where compromise of a low-privileged user yields full root on the host.