Update your Apache Tomcat to avoid Hash collision denial-of-service (DoS)

Update your Apache Tomcat versions 7.0.x, 6.0.x and 5.5.x to the latest released versions 7.0.23, 6.0.35 and 5.5.35, this avoids the hash collision dos vulnerability.

Analysis of the recent hash collision vulnerability identified unrelated inefficiencies with Apache Tomcat's handling of large numbers of parameters and parameter values. These inefficiencies could allow an attacker, via a specially crafted request, to cause large amounts of CPU to be used which in turn could create a denial of service. The issue was addressed by modifying the Tomcat parameter handling code to efficiently process large numbers of parameters and parameter values.

Get the updates from here:
http://tomcat.apache.org