Tomcat Security Issue - Authentication Bypass and Information Disclosure

A new security issue has been reported in Apache Tomcat versions 7 through 7.0.20, 6 through 6.0.33 and 5.5.0 through 5.5.33.
According to the Tomcat mailing lists:

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"Apache Tomcat supports the AJP protocol which is used with reverse proxies to pass requests and associated data about the request from the reverse proxy to Tomcat. The AJP protocol is designed so that when a request includes a request body, an unsolicited AJP message is sent to Tomcat that includes the first part (or possibly all) of the request body. In certain circumstances, Tomcat did not process this message as a request body but as a new request. This permitted an attacker to have full control over the AJP message which allowed an attacker to (amongst other things): - insert the name of an authenticated user

- insert any client IP address (potentially bypassing any client IP address filtering)
- trigger the mixing of responses between users

The following AJP connector implementations are not affected:

org.apache.jk.server.JkCoyoteHandler (5.5.x - default, 6.0.x - default)

The following AJP connector implementations are affected:
org.apache.coyote.ajp.AjpProtocol (6.0.x, 7.0.x - default)
org.apache.coyote.ajp.AjpNioProtocol (7.0.x)
org.apache.coyote.ajp.AjpAprProtocol (5.5.x, 6.0.x, 7.0.x)

Further, this issue only applies if all of the following are are true for at least one resource:
- POST requests are accepted
- The request body is not processed

Example: See https://issues.apache.org/bugzilla/show_bug.cgi?id=51698

Mitigation:

Users of affected versions should apply one of the following mitigations:
- Upgrade to a version of Apache Tomcat that includes a fix for this issue when available
- Apply the appropriate patch
 - 7.0.x http://svn.apache.org/viewvc?rev=1162958&view=rev
 - 6.0.x http://svn.apache.org/viewvc?rev=1162959&view=rev
 - 5.5.x http://svn.apache.org/viewvc?rev=1162960&view=rev
- Configure the reverse proxy and Tomcat's AJP connector(s) to use the requiredSecret attribute
- Use the org.apache.jk.server.JkCoyoteHandler AJP connector (not available for Tomcat 7.0.x)"