CallBackery versions before 0.62.0 for Perl accept session cookies of any age sent in the X-Session-Cookie header. cookieConf() rejects a cookie older than 300 seconds only when it arrives in the xsc query parameter. The same cookie sent in the X-Session-Cookie header is accepted however old it is. A session cookie that leaks through a log, a Referer header or browser history authenticates as its user indefinitely.