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

The undici up to version 5.8.3, is vulnerable to Server-side Request Forgery (SSRF). When an application takes the user input into the 'path/pathname' option of 'undici.request' attacker can induce the server-side application to make unintented requests.

If a victim specifies a URL such as 'http://127.0.0.1' or '//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.

— Red Hat

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.