Prototype pollution in form-data-objectizer via bracket-notation form keys
Priority HIGH 75CWE-1321Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- None · High · Low
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub.
Summary
form-data-objectizer converts FormData to object. Prior to 1.0.1, form-data-objectizer walks bracket-notation form keys (e.g. name[sub]) into nested objects without filtering __proto__, constructor, or prototype. A single HTTP form field whose name starts with __proto__[...] causes the library to mutate Object.prototype, which is a prototype pollution primitive of the entire Node.js process. This vulnerability is fixed in 1.0.1.
Why it matters now
Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00282 20th percentileScored 2026-11-07
Fix Fixed form-data-objectizer (kaspernj): 1.0.1form-data-objectizer (npm): 1.0.1
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- Yes
- 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 |
|---|---|---|---|---|---|
| kaspernj | form-data-objectizer | before 1.0.1 | 1.0.1 | Patch available | CNA |
| — | form-data-objectizer (npm) | before 1.0.1 | 1.0.1 | Patch available | GHSA-m2hg-wjq3-28wq |
- form-data-objectizer Vendorkaspernj Affected before 1.0.1 Fixed in 1.0.1 Patch available CNA
- form-data-objectizer (npm) Vendor— Affected before 1.0.1 Fixed in 1.0.1 Patch available GHSA-m2hg-wjq3-28wq
Remediation
- Fix · CNA form-data-objectizer (kaspernj) Fixed in 1.0.1
- Fix · GHSA-m2hg-wjq3-28wq form-data-objectizer (npm) Fixed in 1.0.1 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-46510
- 2026-10-03 Alias added: GHSA-m2hg-wjq3-28wq
References
Sources
- CVE-2026-46510 · CVE Program
- CVE-2026-46510 · NVD
- FIRST EPSS
- GHSA-m2hg-wjq3-28wq · 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