SvelteKit allows XSS via tracked search_params

published 2025-04-14 18 mo ago modified 2026-06-17 4 mo ago also EUVD-2025-11140 , GHSA-6q87-84jw-cjhp

cvss: 5.4; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 24%
public exploits: 0; none known

SvelteKit is a framework for rapidly developing robust, performant web applications using Svelte. Prior to 2.20.6 , 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. This vulnerability is fixed in 2.20.6.

Patch / fix

fixed in 3 links 2

npm @sveltejs/kit 2.20.6
svelte kit 2.20.6
svelte sveltekit 2.20.6

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: partial
Assessed: 18 mo ago (2025-04-16)

Exploit prediction

0.31% chance of exploitation in the next 30 days, higher than 24% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	5.4	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
GitHub	3.1	5.4	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N

Affected packages

ecosystem	package	affected	fixed in
npm	@sveltejs/kit	>=2.0.0, <2.20.6	2.20.6

Affected products

sveltejs kit

Classification

Weakness

CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.

Summary