SvelteKit (@sveltejs/kit) from 2.10.0 before 3.0.0 contains a path traversal vulnerability in the vite preview server on Windows that allows unauthenticated attackers to read files outside the prerendered output directory. Attackers who can reach the preview server through network access or a tunnel can send crafted requests to expose source code, configuration, or credentials readable by the server process.

SvelteKit (@sveltejs/kit) before 3.0.0 contains a cross-site scripting vulnerability in prerendered pages because a cache-control header value set via setHeaders is inserted without escaping into a <meta http-equiv="cache-control"> tag. An attacker who can influence that untrusted value at prerender time can break out of the content attribute and inject HTML or JavaScript that executes when users visit the page.

SvelteKit (@sveltejs/kit) before 3.0.0 contains an open redirect vulnerability in enhanced form actions (use:enhance) on routes accepting paths beginning with a double slash. Attackers can craft action paths starting with // that become protocol-relative URLs, causing non-redirect form results to navigate victims to attacker-controlled sites.

SvelteKit (@sveltejs/kit) versions >=2.49.0 and <=2.52.1 with experimental remote functions and form enabled contain a CPU exhaustion vulnerability in form deserialization. An attacker can send malformed form data to cause the server to become unresponsive while processing the request, resulting in denial of service. Fixed in 2.52.2.

SvelteKit (@sveltejs/kit) versions >=2.49.0 and <=2.52.1 with experimental remote functions (experimental.remoteFunctions) and form enabled contain a memory exhaustion vulnerability in remote form deserialization. Malformed form data can cause excessive memory allocation, crashing the server process and resulting in denial of service. Fixed in 2.52.2.