Red Hat Enterprise Linux: RHSA-2013-0623-01 Important DoS Risk

Apache Tomcat is a servlet container.
It was found that when an application used FORM authentication, along with another component that calls request.setUserPrincipal() before the call to FormAuthenticator#authenticate() (such as the Single-Sign-On valve), it was possible to bypass the security constraint checks in the FORM authenticator by appending "/j_security_check" to the end of a URL. A remote attacker with an authenticated session on an affected application could use this flaw to circumvent authorization controls, and thereby access resources not permitted by the roles associated with their authenticated session. (CVE-2012-3546)
A flaw was found in the way Tomcat handled sendfile operations when using the HTTP NIO (Non-Blocking I/O) connector and HTTPS. A remote attacker could use this flaw to cause a denial of service (infinite loop). The HTTP blocking IO (BIO) connector, which is not vulnerable to this issue, is used by default in Red Hat Enterprise Linux 6. (CVE-2012-4534)
Multiple weaknesses were found in the Tomcat DIGEST authentication implementation, effectively reducing the security normally provided by DIGEST authentication. A remote attacker could use these flaws to perform replay attacks in some circumstances. (CVE-2012-5885, CVE-2012-5886, CVE-2012-5887)
Users of Tomcat should upgrade to these updated packages, which correct these issues. Tomcat must be restarted for this update to take effect.