### [CVE-2019-17569](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-17569)
![](https://img.shields.io/static/v1?label=Product&message=Apache%20Tomcat&color=blue)
![](https://img.shields.io/static/v1?label=Version&message=n%2Fa&color=blue)
![](https://img.shields.io/static/v1?label=Vulnerability&message=HTTP%20Request%20Smuggling&color=brighgreen)

### 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.

### POC

#### Reference
- https://www.oracle.com/security-alerts/cpujan2021.html
- https://www.oracle.com/security-alerts/cpujan2021.html
- https://www.oracle.com/security-alerts/cpujul2020.html
- https://www.oracle.com/security-alerts/cpujul2020.html
- https://www.oracle.com/security-alerts/cpuoct2020.html
- https://www.oracle.com/security-alerts/cpuoct2020.html

#### Github
- https://github.com/Live-Hack-CVE/CVE-2019-17569
- https://github.com/mklmfane/betvictor
- https://github.com/mo-xiaoxi/HDiff
- https://github.com/raner/projo