SvelteKit before 3.0.0 contains a server-side request forgery vulnerability that allows remote attackers to reach internal services because self-fetch fallbacks follow HTTP redirects automatically. Attackers can manipulate the Host or forwarded headers to point fallback requests at their server, which redirects them to internal services.

SvelteKit before 2.69.1 fails to properly validate remote form function payload sizes, allowing attackers to crash the Node process by sending large payloads. Repeated exploitation causes denial of service by repeatedly crashing the application process.