CVE-2023-29003: SvelteKit vulnerable to Cross-Site Request Forgery

April 4, 2023 (updated October 18, 2026)

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 it’s users. The protection is implemented at kit/src/runtime/server/respond.js#L52. While the implementation does a sufficient job in mitigating common CSRF attacks, the protection can be bypassed by simply specifying a different Content-Type header value.

References

Code Behaviors & Features

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