Fixed in Apache Tomcat 7.0.21

Important: Authentication bypass and information disclosure CVE-2011-3190

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 permitting authentication bypass and information disclosure. This vulnerability only occurs when all of the following are true:

• The org.apache.jk.server.JkCoyoteHandler AJP connector is not used
• POST requests are accepted
• The request body is not processed

This was fixed in revision 1162958.

This was reported publicly on 20th August 2011.

Affects: 7.0.0-7.0.20

Mitigation options:

• Upgrade to Tomcat 7.0.21
• Apply the appropriate patch
• Configure both Tomcat and the reverse proxy to use a shared secret.
  (It is “requiredSecret” attribute in AJP <Connector>, “worker.workername.secret” directive for mod_jk. The mod_proxy_ajp module currently does not support shared secrets).

References:

• AJP Connector documentation (Tomcat 7.0)
• workers.properties configuration (mod_jk)