Vulnerability · Published Oct 15, 2025 · Assigned by GitHub_M

CVE-2025-62381sveltekit-superforms Prototype Pollution in `parseFormData` function of `formData.js`

High 8.3

In plain English

A high-severity prototype pollution in sveltekit-superforms from ciscoheat. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.7% (higher than 54% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)8.3High

Exploit odds (30 days)0.7%top 45.5% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

sveltekit-superforms makes SvelteKit forms a pleasure to use. sveltekit-superforms v2.27.3 and prior are susceptible to a prototype pollution vulnerability within the parseFormData function of formData.js. An attacker can inject string and array properties into Object.prototype, leading to denial of service, type confusion, and potential remote code execution in downstream applications that rely on polluted objects. This vulnerability is fixed in 2.27.4.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
npm	sveltekit-superforms	2.27.4	GHSA-hwmc-4c8j-xxj7

Affected products (as reported)

Vendor	Product	Versions
ciscoheat	sveltekit-superforms	< 2.27.4

Weakness: CWE-1321 · Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:H/SC:L/SI:L/SA:L

References

https://github.com/ciscoheat/sveltekit-superforms/security/advisories/GHSA-hwmc-4c8j-xxj7 x_refsource_CONFIRM
https://github.com/ciscoheat/sveltekit-superforms/commit/4a1310dd1a94176bb22036662c530dad48059ca4 x_refsource_MISC