Apache Tomcat 5.5.11 through 5.5.25 and 6.0.0 through 6.0.15, when the native APR connector is used, does not properly handle an empty request to the SSL port, which allows remote attackers to trigger handling of "a duplicate copy of one of the recent requests," as demonstrated by using netcat to send the empty request.
We recommend upgrading to a version of this component that is not vulnerable to this specific issue.
Note: If this component is included as a bundled/transitive dependency of another component, there may not be an upgrade path. In this instance, we recommend contacting the maintainers who included the vulnerable package. Alternatively, we recommend investigating alternative components or a potential mitigating control.