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High severityOSV Advisory· Published Oct 15, 2025· Updated Apr 15, 2026

CVE-2025-62381

CVE-2025-62381

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

Versions sourced from the GitHub Security Advisory.

PackageAffected versionsPatched versions
sveltekit-superformsnpm
< 2.27.42.27.4

Affected products

1

Patches

1
4a1310dd1a94

Fixed prototype pollution when using dataType: 'json'

https://github.com/ciscoheat/sveltekit-superformsAndreas SöderlundOct 15, 2025via ghsa
commit
2 files changed · +7 −1
  • CHANGELOG.md+1 −1 modified
    @@ -5,7 +5,7 @@ Headlines: Added, Changed, Deprecated, Removed, Fixed, Security
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## [2.27.3] - 2025-10-14
+## [2.27.4] - 2025-10-14
 
 ### Security
  • src/lib/traversal.ts+6 −0 modified
    @@ -52,6 +52,12 @@ export function traversePath<T extends object>(
 	modifier?: (data: PathData) => undefined | unknown | void
 ): PathData | undefined {
 	if (!realPath.length) return undefined;
+
+	// Prevent prototype injection
+	if (realPath.includes('__proto__') || realPath.includes('prototype')) {
+		throw new Error("Cannot set an object's `__proto__` or `prototype` property");
+	}
+
 	const path = [realPath[0]];
 
 	let parent = obj;

Vulnerability mechanics

Generated by null/stub on May 9, 2026. Inputs: CWE entries + fix-commit diffs from this CVE's patches. Citations validated against bundle.

References

4

News mentions

0

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