Svelte 2.6.6 is a minor patch release following 2.6.5, both iterations of the "magical disappearing UI framework" focused on shifting work from the browser to compile time, resulting in highly performant web applications. Examining the package data, the core development dependencies remain identical between the two versions, indicating a consistent development environment and toolchain. This includes essential tools for linting (eslint), bundling (rollup), testing (mocha, jsdom, nyc, codecov, nightmare), and TypeScript support.
The key distinction lies in the "dist" section, specifically the "unpackedSize". Version 2.6.6 has an unpacked size of 2593791 bytes, slightly larger than 2.6.5's 2593490 bytes, a difference of only 301 bytes. This suggests that the changes were minimal and were likely bug fixes or very minor improvements. The release date for 2.6.6 is a few hours after 2.6.5, further signifying that the newer version addressed something specific that needed immediate attention.
For developers using Svelte, this implies that upgrading from 2.6.5 is highly recommended due to the potential bug fixes. While the change is minimal, staying on the latest patch version ensures a more stable and reliable experience. Svelte's philosophy of compiling away makes these small improvements potentially impactful, so users should prefer the latest version. With it's MIT license, the project allows for a great degree of freedom.
All the vulnerabilities related to the version 2.6.6 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