GoAhead WebServer before 2.1.6 allows remote attackers to cause a denial of service (NULL pointer dereference and daemon crash) via an invalid URL, related to the websSafeUrl function.
https://euvd.enisa.europa.eu/vulnerability/EUVD-2003-1558
http://data.goahead.com/Software/Webserver/2.1.8/release.htm#null-pointer-crash-in-webssafeurl