Svelte is a UI framework known for its "disappearing" act, meaning it shifts the workload from the browser to the compile step, resulting in highly performant web applications. Comparing versions 1.23.0 and 1.23.1 reveals a subtle but important update. Both versions share the same core functionality and boast an extensive set of development dependencies, including tools for testing (mocha, nyc, jsdom), linting (eslint), bundling (rollup), and transpilation (babel). These dependencies highlight Svelte's commitment to a robust and well-tested development environment.
The key difference lies in the release date, with version 1.23.1 released just hours after 1.23.0. This suggests that version 1.23.1 likely includes bug fixes or minor adjustments to the original 1.23.0 release. For developers, this means that while the feature set remains consistent, upgrading to the latest patch version (1.23.1) ensures a more stable and reliable experience. Developers should prioritize using the newest patch to benefit from any immediate fixes. These versions support features and tools typical for the time of release. The library is under the MIT license, meaning it is very permissive about usage.
All the vulnerabilities related to the version 1.23.1 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