Arch Linux: Open redirect (CVE-2021-29622)

A security issue has been found in Prometheus before version 2.27.1. In 2.23.0, Prometheus changed its default UI to the New UI. To ensure a seamless transition, the URL's prefixed by /new redirect to /. Due to a bug in the code, it is possible for an attacker to craft an URL that can redirect to any other URL in the /new endpoint.

If a user visits a Prometheus server with a specially crafted address (e.g. http://127.0.0.1:9090/new/new<url>), they can be redirected to an arbitrary URL. E.g. if a user visits http://127.0.0.1:9090/new/newhttp://www.google.com/, they will be redirected to http://google.com.

Note: Users who use a --web.external-url= flag with a path (e.g. --web.external-url=http://example.com/prometheus) are not affected.