MailEnable < 10.54 Reflected XSS in Message Parameter of Mobile/Compose.aspx

MailEnable versions prior to 10.54 contain a reflected cross-site scripting (XSS) vulnerability in the Message parameter of /Mobile/Compose.aspx. The Message value is not properly sanitized when processed via a GET request and is reflected into a JavaScript context in the response. By supplying a crafted payload that terminates the existing script block/function, injects attacker-controlled JavaScript, and comments out the remaining code, a remote attacker can execute arbitrary JavaScript in a victim’s browser when the victim opens the crafted reply URL. Successful exploitation can redirect victims to malicious sites, steal non-HttpOnly cookies, inject arbitrary HTML or CSS, and perform actions as the authenticated user.