Svelte 4.2.2 represents a minor update to the popular Svelte framework, building upon the features and stability of version 4.2.1. Both versions aim to empower developers to create "cybernetically enhanced web apps," emphasizing performance and a streamlined development experience. Looking at the dependencies, the core difference lies on a newer version of magic-string, going from 0.30.0 to 0.30.4. While seemingly small, this update could include bug fixes or performance enhancements within the source code transformation process that magic-string provides, benefiting developers by improving build times or code output. Another change is the jsdom dependency, where the newer version shifts from ^21.1.2 to 22.0.0. The unpacked size also increased slightly from 2625602 to 2628157, probably reflecting the changes made on the package. For developers, this upgrade signifies a continued commitment to maintaining and refining the Svelte ecosystem. Existing Svelte projects should be able to upgrade seamlessly, gaining any potential improvements from the updated magic-string and jsdom packages. Always refer to the official Svelte changelog for a detailed breakdown of specific fixes and enhancements included in the 4.2.2 release.
All the vulnerabilities related to the version 4.2.2 of the package
Svelte has a potential mXSS vulnerability due to improper HTML escaping
A potential XSS vulnerability exists in Svelte for versions prior to 4.2.19.
Svelte improperly escapes HTML on server-side rendering. It converts strings according to the following rules:
" -> "& -> &< -> <& -> &The assumption is that attributes will always stay as such, but in some situation the final DOM tree rendered on browsers is different from what Svelte expects on server-side rendering. This may be leveraged to perform XSS attacks. More specifically, this can occur when injecting malicious content into an attribute within a <noscript> tag.
A vulnerable page (+page.svelte):
<script>
import { page } from "$app/stores"
// user input
let href = $page.url.searchParams.get("href") ?? "https://example.com";
</script>
<noscript>
<a href={href}>test</a>
</noscript>
If a user accesses the following URL,
http://localhost:4173/?href=</noscript><script>alert(123)</script>
then, alert(123) will be executed.
XSS, when using an attribute within a noscript tag