Improper Restriction of XML External Entity Reference in Apache Roller 4.0 through 6.1.6 allows an authenticated user with no weblog permissions to read files readable by the Roller process and cause the server to issue outbound HTTP requests to attacker-chosen destinations, by submitting a crafted Atom entry to the AtomPub endpoint. The entry body is parsed with a parser configuration that permits external parameter entities and external DTD subsets, and the parse happens before any per-weblog authorization check and before any check of whether the AtomPub feature is enabled, so the endpoint is reachable by any authenticated account on a default installation. Users are recommended to upgrade to Apache Roller 6.1.7 or later, which parses AtomPub entries with a hardened XML configuration and rejects AtomPub requests while the feature is disabled.