A Server-Side Request Forgery (SSRF) vulnerability exists in the ONLYOFFICE ownCloud Integration plugin version 9.12. The vulnerability allows an authenticated administrator to manipulate the Document Server URL parameter at the /apps/onlyoffice/ajax/settings/address endpoint, causing the ownCloud server to send arbitrary requests to attacker-controlled or internal network destinations. This can be used for internal network reconnaissance and TCP port scanning. The vulnerability has a CVSS 3.1 score of 6.5, indicating medium severity.