CVE-2025-32388

Unsanitized search param names cause XSS vulnerability. You are affected if you iterate over all entries of event.url.searchParams inside a server load function. Attackers can exploit it by crafting a malicious URL and getting a user to click a link with said URL.

Details

SvelteKit tracks which parameters in event.url.searchParams are read inside server load functions. If the application iterates over the these parameters, the uses.search_params array included in the boot script (embedded in the server-rendered HTML) will have any search param name included in unsanitized form.

packages/kit/src/runtime/server/utils.js:150 has the stringify_uses(node) function which prints these out.

Reproduction

In a +page.server.js or +layout.server.js:

/** @type {import('@sveltejs/kit').Load} */
export function load(event) {
  const values = {};

  for (const key of event.url.searchParams.keys()) {
    values[key] = event.url.searchParams.get(key);
  }
}

If a user visits the page in question via a link containing ?</script/><script>window.pwned%3D1</script/>, the </script> will be included verbatim in the payload, causing the embedded script to be executed.

It is not necessary to return the parameter value from load or render it in the page, only to read it (which causes it to be tracked as a dependency) while load is running.

Any application that iterates over all values in event.url.searchParams in a load function in +page.server.js or +layout.server.js (directly or indirectly) is vulnerable to XSS.

Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.

CVE-2025-32388 has a CVSS score of 5.4 (Medium). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.20.6); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2025-32388? CVE-2025-32388 is a medium-severity cross-site scripting (XSS) vulnerability in @sveltejs/kit (npm), affecting versions >= 2.0.0, < 2.20.6. It is fixed in 2.20.6. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
2. How severe is CVE-2025-32388? CVE-2025-32388 has a CVSS score of 5.4 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of @sveltejs/kit are affected by CVE-2025-32388? @sveltejs/kit (npm) versions >= 2.0.0, < 2.20.6 is affected.
4. Is there a fix for CVE-2025-32388? Yes. CVE-2025-32388 is fixed in 2.20.6. Upgrade to this version or later.
5. Is CVE-2025-32388 exploitable, and should I be worried? Whether CVE-2025-32388 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2025-32388 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2025-32388? Upgrade @sveltejs/kit to 2.20.6 or later.