Description

The refactoring present in Apache Tomcat 9.0.28 to 9.0.30, 8.5.48 to 8.5.50 and 7.0.98 to 7.0.99 introduced a regression. The result of the regression was that invalid Transfer-Encoding headers were incorrectly processed leading to a possibility of HTTP Request Smuggling if Tomcat was located behind a reverse proxy that incorrectly handled the invalid Transfer-Encoding header in a particular manner. Such a reverse proxy is considered unlikely.

Mitigation

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.

Related links:

• http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2019-17569

• http://tomcat.apache.org/security-7.html#Fixed_in_Apache_Tomcat_7.0.100

• http://tomcat.apache.org/security-8.html#Fixed_in_Apache_Tomcat_8.5.51

• http://tomcat.apache.org/security-9.html#Fixed_in_Apache_Tomcat_9.0.31

• https://lists.apache.org/thread.html/r88def002c5c78534674ca67472e035099fbe088813d50062094a1390%40%3Cannounce.tomcat.apache.org%3E