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

zot is ancontainer image/artifact registry based on the Open Container Initiative Distribution Specification. From 1.3.0 to 2.1.14, 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. This vulnerability is fixed in 2.1.15.