Emlog is an open source website building system. A stored Cross-Site Scripting (XSS) vulnerability exists in the "Twitter"feature of EMLOG Pro 2.5.21 and below. An authenticated user with privileges to post a "Twitter" message can inject arbitrary JavaScript code. The malicious script is stored on the server and gets executed in the browser of any user, including administrators, when they click on the malicious post to view it. This issue does not currently have a fix.