Omnispace Agora Project before 26.10.0 contains a reflected cross-site scripting vulnerability that allows unauthenticated attackers to inject malicious HTML attributes by manipulating the visioUrl parameter, which was not routed through the URL-sanitizing branch of the parameter filter and was urldecoded after filtering. Attackers can craft a malicious URL containing the visioUrl parameter with an attribute breakout payload to execute arbitrary JavaScript in the victim's browser pre-authentication, with the issue fixed in version 26.10.0 via changes to app/Common/Req.php.