query_params.cpp in cxxtools before 2.2.1 allows remote attackers to cause a denial of service (infinite recursion and crash) via an HTTP query that contains %% (double percent) characters.
https://exchange.xforce.ibmcloud.com/vulnerabilities/90564
http://www.tntnet.org/download/cxxtools-2.2.1/Releasenotes-2.2.1.markdown
http://www.securityfocus.com/bid/65020
http://secunia.com/advisories/56363
http://seclists.org/oss-sec/2014/q1/116
http://seclists.org/oss-sec/2014/q1/112
http://lists.fedoraproject.org/pipermail/package-announce/2014-January/127445.html