Apache Tomcat is a servlet container for the Java Servlet and JavaServerPages (JSP) technologies.It was found that the Java hashCode() method implementation was susceptibleto predictable hash collisions. A remote attacker could use this flaw tocause Tomcat to use an excessive amount of CPU time by sending an HTTPrequest with a large number of parameters whose names map to the same hashvalue. This update introduces a limit on the number of parameters processedper request to mitigate this issue. The default limit is 512 forparameters and 128 for headers. These defaults can be changed by settingthe org.apache.tomcat.util.http.Parameters.MAX_COUNT andorg.apache.tomcat.util.http.MimeHeaders.MAX_COUNT system properties.(CVE-2011-4858)It was found that Tomcat did not handle large numbers of parameters andlarge parameter values efficiently. A remote attacker could make Tomcatuse an excessive amount of CPU time by sending an HTTP request containing alarge number of parameters or large parameter values. This updateintroduces limits on the number of parameters and headers processed perrequest to address this issue. Refer to the CVE-2011-4858 description forinformation about the org.apache.tomcat.util.http.Parameters.MAX_COUNT andorg.apache.tomcat.util.http.MimeHeaders.MAX_COUNT system properties.(CVE-2012-0022) Red Hat would like to thank oCERT for reporting CVE-2011-4858. oCERTacknowledges Julian Wälde and Alexander Klink as the original reporters ofCVE-2011-4858.Users of Tomcat should upgrade to these updated packages, which correctthese issues. Tomcat must be restarted for this update to take effect.