The ExpandCert function in Apache-SSL before apache_1.3.41+ssl_1.59 does not properly handle (1) '/' and (2) '=' characters in a Distinguished Name (DN) in a client certificate, which might allow remote attackers to bypass authentication via a crafted DN that triggers overwriting of environment variables.
https://exchange.xforce.ibmcloud.com/vulnerabilities/41618
http://www.vupen.com/english/advisories/2008/1079/references
http://www.securitytracker.com/id?1019784
http://www.securityfocus.com/bid/28576
http://www.securityfocus.com/archive/1/490386/100/0/threaded