CVE-2026-12411: lxd allows Cross-guest volume hijack via DevLXD device patch

A guest can mount another guest’s custom storage volume over /dev/lxd and read or write its contents without owning it. The DevLXD storage API blocks access to volumes you don’t own, but the instance device-update path that attaches a volume to a container without checks ownership. Any guest in a project with security.devlxd.management.volumes enabled can attach a volume belonging to a different guest by naming it in a device PATCH, giving one tenant full read and write access to another tenant’s volume data.