Svelte is a UI framework that takes a different approach, compiling your code to highly efficient vanilla JavaScript at build time. This results in smaller bundle sizes and better runtime performance compared to traditional frameworks that rely on virtual DOM diffing. Version 1.40.2 is a minor update following 1.40.1, both sharing the core functionality of the framework. The primary difference lies in the updated development dependencies. Specifically, prettier, a code formatter, was updated from version 1.4.1 to 1.7.0. This change primarily impacts the development workflow, ensuring consistent code styling across the project. Developers using Svelte benefit from its reactive statements, component-based architecture, and smooth transitions. The updated prettier version will auto-format the code based on configured rules and make the codebase consistent by enforcing those rules. Beyond this update, Svelte offers tools like rollup, typescript, and eslint integration for a modern development experience, enabling creating performant and accessible web applications. Both versions provide the core benefits of Svelte, the new version provides a slightly improved dev tool.
All the vulnerabilities related to the version 1.40.2 of the package
Svelte vulnerable to XSS when using objects during server-side rendering
The package svelte before 3.49.0 is vulnerable to Cross-site Scripting (XSS) due to improper input sanitization and to improper escape of attributes when using objects during SSR (Server-Side Rendering). Exploiting this vulnerability is possible via objects with a custom toString() function.
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