A Server-Side Request Forgery (SSRF) vulnerability exists in the ONLYOFFICE ownCloud Integration plugin version 9.12. The /apps/onlyoffice/ajax/settings/address endpoint does not sufficiently validate the user-supplied Document Server URL before initiating outbound connections. An authenticated administrator can manipulate the document server parameter to cause the ownCloud server to send arbitrary requests to attacker-controlled destinations, including localhost and internal network hosts. This allows internal network reconnaissance and TCP port scanning based on differences in server responses.