sveltekit-superforms Prototype Pollution in `parseFormData` function of `formData.js`
Priority HIGH 69CWE-1321Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- High
- Attack requirements
- Present
- Impact type
- —
- Confidentiality · integrity · availability
- Low · Low · High
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub.
Summary
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.
Why it matters now
Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00732 54th percentileScored 2026-11-07
Fix Fixed sveltekit-superforms (ciscoheat): 2.27.4sveltekit-superforms (npm): 2.27.4
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| ciscoheat | sveltekit-superforms | before 2.27.4 | 2.27.4 | Patch available | CNA |
| — | sveltekit-superforms (npm) | before 2.27.4 | 2.27.4 | Patch available | GHSA-hwmc-4c8j-xxj7 |
- sveltekit-superforms Vendorciscoheat Affected before 2.27.4 Fixed in 2.27.4 Patch available CNA
- sveltekit-superforms (npm) Vendor— Affected before 2.27.4 Fixed in 2.27.4 Patch available GHSA-hwmc-4c8j-xxj7
Remediation
- Fix · CNA sveltekit-superforms (ciscoheat) Fixed in 2.27.4
- Fix · GHSA-hwmc-4c8j-xxj7 sveltekit-superforms (npm) Fixed in 2.27.4 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2025-62381
- 2026-10-03 Alias added: GHSA-hwmc-4c8j-xxj7
- 2026-10-09 EPSS moved to the 50th–90th percentile
References
Sources
- CVE-2025-62381 · CVE Program
- CVE-2025-62381 · NVD
- FIRST EPSS
- GHSA-hwmc-4c8j-xxj7 · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences