Apache-SSL 1.3.28+1.52 and earlier, with SSLVerifyClient set to 1 or 3 and SSLFakeBasicAuth enabled, allows remote attackers to forge a client certificate by using basic authentication with the "one-line DN" of the target user.
https://exchange.xforce.ibmcloud.com/vulnerabilities/15065
http://www.securityfocus.com/bid/9590
http://www.apache-ssl.org/advisory-20040206.txt
http://marc.info/?l=bugtraq&m=107619127531765&w=2
http://lists.grok.org.uk/pipermail/full-disclosure/2004-February/016870.html