Svelte version 2.9.5 is a minor update to the popular "magical disappearing UI framework," building upon the previous stable release, 2.9.4. Both versions share the same core description and MIT license, indicating a continued commitment to open-source principles. Developed by Rich Harris, Svelte aims to provide a streamlined development experience by shifting much of the framework's work to compile time, resulting in smaller, faster web applications.
A key difference between these releases lies in their distribution details. Version 2.9.5 has a slightly larger unpacked size of 2595136 bytes compared to 2.9.4's 2573373 bytes and more files (17 vs 15), hinting at possible additions or adjustments to the core library or tooling. The release dates also differentiate them, with 2.9.5 being released on July 17, 2018, and 2.9.4 on July 15, 2018.
Developers considering upgrading from 2.9.4 to 2.9.5 should investigate the specific changes contributing to the increased size and file count – these changes may contain bug fixes, performance improvements, or new features. Although the devDependencies are identical, indicating no changes to development tooling, the subtle differences in the distributed package warrant a closer look for those seeking optimal performance and stability in their Svelte applications. Svelte's approach to UI development, by compiling components to highly efficient vanilla JavaScript during build time, makes it suitable for performance-critical applications where minimizing runtime overhead is essential.
All the vulnerabilities related to the version 2.9.5 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