The following problems were fixed in Apache Tomcat version 7.0.21:
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.
Affected Apache Tomcat versions (7.0.0 - 7.0.20).
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