The IPv6 URI parsing routines in the apr-util library for Apache 2.0.50 and earlier allow remote attackers to cause a denial of service (child process crash) via a certain URI, as demonstrated using the Codenomicon HTTP Test Tool.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A11380
https://exchange.xforce.ibmcloud.com/vulnerabilities/17382
http://www.redhat.com/support/errata/RHSA-2004-463.html