WWBN AVideo is an open source video platform. In versions 26.0 and prior, the AVideo YPTSocket plugin's caller feature renders incoming call notifications using the jQuery Toast Plugin, passing the caller's display name directly as the heading parameter. The toast plugin constructs the heading as raw HTML ('<h2>' + heading + '</h2>') and inserts it into the DOM via jQuery's .html() method, which parses and executes any embedded HTML or script content.

An attacker can set their display name to an XSS payload and trigger code execution on any online user's browser simply by initiating a call - no victim interaction is required beyond being connected to the WebSocket. At time of publication, there are no publicly available patches.