Apache Tomcat is a servlet container for the Java Servlet and JavaServer Pages technologies. It was found that a fix for a previous security flaw introduced a regression that could cause a denial of service in Tomcat 7. A remote attacker could use this flaw to consume an excessive amount of CPU on the Tomcat server by sending a specially crafted request to that server. It was found that when Tomcat 7 processed a series of HTTP requests in which at least one request contained either multiple content-length headers, or one content-length header with a chunked transfer-encoding header, Tomcat would incorrectly handle the request. A remote attacker could use this flaw to poison a web cache, perform cross-site scripting attacks, or obtain sensitive information from other requests. It was discovered that the fix for CVE-2012-3544 did not properly resolve a denial of service flaw in the way Tomcat 7 processed chunk extensions and trailing headers in chunked requests. A remote attacker could use this flaw to send an excessively long request that, when processed by Tomcat, could consume network bandwidth, CPU, and memory on the Tomcat server. Note that chunked transfer encoding is enabled by default. All Tomcat 7 users are advised to upgrade to these updated packages, which contain backported patches to correct these issues. Tomcat must be restarted for this update to take effect.