CVE-2022-35949: `undici.request` vulnerable to SSRF using absolute URL on `pathname`

Vulnerability summary

CVE-2022-35949 is a critical (CVSS 9.8) Server-Side Request Forgery vulnerability in nodejs undici. EPSS estimates a 1.93% chance of exploitation in the next 30 days, higher than 79.9% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 12-08-2022
   PublishedVulnerability first disclosed.
2. 22-04-2025
   Last modifiedVulnerability information updated.

Description

undici is an HTTP/1.1 client, written from scratch for Node.js.`undici` is vulnerable to SSRF (Server-side Request Forgery) when an application takes in **user input** into the `path/pathname` option of `undici.request`. If a user specifies a URL such as `http://127.0.0.1` or `//127.0.0.1` ```js const undici = require("undici") undici.request({origin: "http://example.com", pathname: "//127.0.0.1"}) ``` Instead of processing the request as `http://example.org//127.0.0.1` (or `http://example.org/http://127.0.0.1` when `http://127.0.0.1 is used`), it actually processes the request as `http://127.0.0.1/` and sends it to `http://127.0.0.1`. If a developer passes in user input into `path` parameter of `undici.request`, it can result in an _SSRF_ as they will assume that the hostname cannot change, when in actual fact it can change because the specified path parameter is combined with the base URL. This issue was fixed in `undici@5.8.1`. The best workaround is to validate user input before passing it to the `undici.request` call.

• CWE-918Server-Side Request ForgeryThe web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.