Advisories for Npm/@Sveltejs/Kit package

2026

SvelteKit has deserialization expansion in unvalidated `form` remote function leading to Denial of Service (experimental only)

Some relatively small inputs can cause very large files arrays in form handlers. If the SvelteKit application code doesn't check files.length or individual files' sizes and performs expensive processing with them, it can result in Denial of Service. Only users with experimental.remoteFunctions: true who are using the form function and are processing the files array without validation are vulnerable.

2025
2024

Improper Input Validation

SvelteKit is a web development kit. In SvelteKit 2, sending a GET request with a body eg {} to a built and previewed/hosted sveltekit app throws Request with GET/HEAD method cannot have body. and crashes the preview/hosting. After this happens, one must manually restart the app. TRACE requests will also cause the app to crash. Prerendered pages and SvelteKit 1 apps are not affected. @sveltejs/adapter-node versions 2.1.2, 3.0.3, and 4.0.1 …

2023

Server-Side Request Forgery (SSRF)

The SvelteKit framework offers developers an option to create simple REST APIs. This is done by defining a +server.js file, containing endpoint handlers for different HTTP methods. SvelteKit provides out-of-the-box cross-site request forgery (CSRF) protection to its users. The protection is implemented at kit/src/runtime/server/respond.js. While the implementation does a sufficient job of mitigating common CSRF attacks, the protection can be bypassed in versions prior to 1.15.2 by simply specifying an …

Incomplete List of Disallowed Inputs

SvelteKit is a web development framework. The SvelteKit framework offers developers an option to create simple REST APIs. This is done by defining a +server.js file, containing endpoint handlers for different HTTP methods. SvelteKit provides out-of-the-box cross-site request forgery (CSRF) protection to its users. While the implementation does a sufficient job in mitigating common CSRF attacks, prior to version 1.15.1, the protection can be bypassed by simply specifying a different …