### [CVE-2021-43824](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-43824)
![](https://img.shields.io/static/v1?label=Product&message=envoy&color=blue)
![](https://img.shields.io/static/v1?label=Version&message=%3C%201.18.6%20&color=brightgreen)
![](https://img.shields.io/static/v1?label=Version&message=%3E%3D%201.19.0%2C%20%3C%201.19.3%20&color=brightgreen)
![](https://img.shields.io/static/v1?label=Version&message=%3E%3D%201.20.0%2C%20%3C%201.20.2%20&color=brightgreen)
![](https://img.shields.io/static/v1?label=Version&message=%3E%3D%201.21.0%2C%20%3C%201.21.1%20&color=brightgreen)
![](https://img.shields.io/static/v1?label=Vulnerability&message=CWE-476%3A%20NULL%20Pointer%20Dereference&color=brightgreen)

### Description

Envoy is an open source edge and service proxy, designed for cloud-native applications. In affected versions a crafted request crashes Envoy when a CONNECT request is sent to JWT filter configured with regex match. This provides a denial of service attack vector. The only workaround is to not use regex in the JWT filter. Users are advised to upgrade.

### POC

#### Reference
No PoCs from references.

#### Github
- https://github.com/ARPSyndicate/cvemon
- https://github.com/ssst0n3/docker_archive