cve/2023/CVE-2023-35944.md

### [CVE-2023-35944](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-35944)
![](https://img.shields.io/static/v1?label=Product&message=envoy&color=blue)
![](https://img.shields.io/static/v1?label=Version&message=%3D%20%3E%3D%201.26.0%2C%20%3C%201.26.4%20&color=brighgreen)
![](https://img.shields.io/static/v1?label=Vulnerability&message=CWE-20%3A%20Improper%20Input%20Validation&color=brighgreen)

### Description

Envoy is an open source edge and service proxy designed for cloud-native applications. Envoy allows mixed-case schemes in HTTP/2, however, some internal scheme checks are case-sensitive. Prior to versions 1.27.0, 1.26.4, 1.25.9, 1.24.10, and 1.23.12, this can lead to the rejection of requests with mixed-case schemes such as `htTp` or `htTps`, or the bypassing of some requests such as `https` in unencrypted connections. With a fix in versions 1.27.0, 1.26.4, 1.25.9, 1.24.10, and 1.23.12, Envoy will now lowercase scheme values by default, and change the internal scheme checks that were case-sensitive to be case-insensitive. There are no known workarounds for this issue.

### POC

#### Reference
- https://github.com/envoyproxy/envoy/security/advisories/GHSA-pvgm-7jpg-pw5g

#### Github
No PoCs found on GitHub currently.