CVE-2026-31801: zot’s create-only policy allows overwrite attempts of existing latest tag (update permission not required)

zot’s dist-spec authorization middleware infers the required action for PUT /v2/{name}/manifests/{reference} as create by default, and only switches to update when the tag already exists and reference != "latest".

as a result, when latest already exists, a user who is allowed to create (but not allowed to update) can still pass the authorization check for an overwrite attempt of latest.