CVE-2026-33945: Incus has an abitrary file write through its systemd-creds options

Incus instances have an option to provide credentials to systemd in the guest. For containers, this is handled through a shared directory. An attacker can use the name of a systemd credential to escape that directory and overwrite arbitrary files on the host system.

This can in turn be used to perform local privilege escalation or cause a DoS.