Cross-site scripting (XSS) vulnerability in libahttp/err.c in OkCupid OKWS (OK Web Server) allows remote attackers to inject arbitrary web script or HTML via the PATH_INFO to a non-existent page, which is not properly handled in a 404 error page.
https://twitter.com/infosecmaverick/status/462573038299803648
https://hackerone.com/reports/3317
https://github.com/okws/okws/commit/e9bedb644d106a043e33e1058bedd1c2c0b2e2e0