Plugin/passwordauth.pm (aka the passwordauth plugin) in ikiwiki 1.34 through 2.47 allows remote attackers to bypass authentication, and login to any account for which an OpenID identity is configured and a password is not configured, by specifying an empty password during the login sequence.
bugs.debian.org/cgi-bin/bugreport.cgi?bug=483770
ikiwiki.info/news/version_2.48/index.html
ikiwiki.info/security/
secunia.com/advisories/30468
www.openwall.com/lists/oss-security/2008/05/31/3
www.securityfocus.com/bid/29479
www.vupen.com/english/advisories/2008/1710
exchange.xforce.ibmcloud.com/vulnerabilities/42798