W3C » Cern Httpd : Security Vulnerabilities, CVEs,

Cross-site scripting (XSS) vulnerability in CERN Proxy Server allows remote attackers to execute script as other users via a link to a non-existent page whose name contains the script, which is inserted into the resulting error page.

The W3C CERN httpd HTTP server allows remote attackers to determine the real pathnames of some commands via a request for a nonexistent URL.