The Tomcat security team has identified three critical vulnerabilities in the Apache Tomcat , an open source web server and servlet container . The vulnerabilities affect 7 and 6 versions .

CVE-2012-4534: Denial of Service(DOS) vulnerability
When using the NIO connector with sendfile and HTTPS enabled, if a
client breaks the connection while reading the response an infinite loop
is entered leading to a denial of service. Tomcat 7.0.0 to 7.0.27 and Tomcat 6.0.0 to 6.0.35 are affected .

CVE-2012-3546 : Apache Tomcat Bypass of security constraints
When using FORM authentication it was possible to bypass the security constraint checks in the FORM authenticator by appending "/j_security_check" to the end of the URL if some other component (such as the Single-Sign-On valve) had called request.setUserPrincipal() before the call to FormAuthenticator#authenticate(). Tomcat 7.0.0 to 7.0.29 and Tomcat 6.0.0 to 6.0.35 are affected .

CVE-2012-4431 Apache Tomcat Bypass of CSRF prevention filter
The CSRF prevention filter could be bypassed if a request was made to a
protected resource without a session identifier present in the request. Tomcat 7.0.0 to 7.0.31 and Tomcat 6.0.0 to 6.0.35 are affected .

Users of affected versions are advised to upgrade their Tomcat with the latest versions.