Arch Linux: Cross-site scripting (CVE-2021-41174)

A security issue has been found in Grafana before version 8.2.3. If an attacker is able to convince a victim to visit a URL referencing a vulnerable page, arbitrary JavaScript content may be executed within the context of the victim's browser.

The user visiting the malicious link must be unauthenticated and the link must be for a page that contains the login button in the menu bar.

There are two ways an unauthenticated user can open a page in Grafana that contains the login button:
- Anonymous authentication is enabled. This means all pages in Grafana would be open for the attack.
- The link is to an unauthenticated page. The following pages are vulnerable:
- /dashboard-solo/snapshot/*
- /dashboard/snapshot/*
- /invite/:code

The url has to be crafted to exploit AngularJS rendering and contain the interpolation binding for AngularJS expressions. AngularJS uses double curly braces for interpolation binding: {{ }}

An example of an expression would be: "{{constructor.constructor(‘alert(1)’)()}}". This can be included in the link URL like this:

https://play.grafana.org/dashboard/snapshot/%7B%7Bconstructor.constructor('alert(1)')()%7D%7D?orgId=1

When the user follows the link and the page renders, the login button will contain the original link with a query parameter to force a redirect to the login page. The URL is not validated and the AngularJS rendering engine will execute the JavaScript expression contained in the URL.