Pagefind DOM clobbering could escalate to Cross-site Scripting (XSS)

Vulnerability Description

Pagefind, a fully static search library, initializes its dynamic JavaScript and WebAssembly files relative to the location of the first script the user loads. This information is gathered by looking up the value of `document.currentScript.src`. Prior to Pagefind version 1.1.1, it is possible to "clobber" this lookup with otherwise benign HTML on the page. This will cause `document.currentScript.src` to resolve as an external domain, which will then be used by Pagefind to load dependencies. This exploit would only work in the case that an attacker could inject HTML to a live, hosted, website. In these cases, this would act as a way to escalate the privilege available to an attacker. This assumes they have the ability to add some elements to the page (for example, `img` tags with a `name` attribute), but not others, as adding a `script` to the page would itself be the cross-site scripting vector. Pagefind has tightened this resolution in version 1.1.1 by ensuring the source is loaded from a valid script element. There are no reports of this being exploited in the wild via Pagefind.

References

• https://github.com/CloudCannon/pagefind/security/advisories/GHSA-gprj-6m2f-j9hx
• https://github.com/webpack/webpack/security/advisories/GHSA-4vvj-4cpr-p986
• https://github.com/CloudCannon/pagefind/commit/14ec96864eabaf1d7d809d5da0186a8856261eeb