PyBlosxom before 1.3.2, when running on certain webservers, allows remote attackers to read arbitrary files via an HTTP request with multiple leading / (slash) characters, which is accessed using the PATH_INFO variable.
https://exchange.xforce.ibmcloud.com/vulnerabilities/24730
http://www.vupen.com/english/advisories/2006/0571
http://www.securityfocus.com/bid/16641
http://sourceforge.net/project/shownotes.php?release_id=391800