What’s Vulnerable › Vulnerabilities

CVE-2026-46510: Prototype pollution in form-data-objectizer via bracket-notation form keys

• Severity: high (CVSS 8.2 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-05-29 · updated 2026-07-21
• Weakness: CWE-1321

Description

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.

Affected products

• kaspernj form-data-objectizer: before 1.0.1

References

• https://github.com/kaspernj/form-data-objectizer/commit/7c54b99408e6e9cd6533b7245bf197dadc2a2dbc
• https://github.com/kaspernj/form-data-objectizer/security/advisories/GHSA-m2hg-wjq3-28wq
• https://github.com/kaspernj/form-data-objectizer/security/advisories/GHSA-m2hg-wjq3-28wq

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