CVE-2025-32388 is a medium-severity (CVSS 5.4) Cross-site Scripting (XSS) vulnerability in @sveltejs/kit. A fix is available for @sveltejs/kit — see the affected versions and patch details below.
SvelteKit allows XSS via tracked search_params
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2025-32388.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2025-32388 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,636 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
@sveltejs/kitnpmDescription
Summary
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.
Impact
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @sveltejs/kit | ≥ 2.0.0&&< 2.20.6 | 2.20.6npm install @sveltejs/kit@2.20.6 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @sveltejs/kit, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @sveltejs/kit to 2.20.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-32388 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2025-32388 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2025-32388. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2025-32388 in your dependencies?
O3 Security finds CVE-2025-32388 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.