CVE-2026-81494

Incus extracts an imported unified image's top-level files directly into the instance directory and later writes to some of those paths as root without checking for symlinks. An image can ship backup.yaml and network/resolv.conf as absolute symlinks, so UpdateInstanceBackupFile (at instance creation) and the OCI network setup in startCommon (at container start) follow them and write root-owned files anywhere on the host. Because the oci.dns.domain and oci.dns.search values accept line breaks, the resolv.conf content is attacker-controlled, which allows for example planting a file in /etc/cron.d for root command execution. The writes are not confined to the instance root and the dns values are not validated against newlines.