Prototype Pollution in Kaspernj Form-Data-Objectizer

CVE-2026-46510

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.

Vulnerability class: Prototype Pollution

Published · last modified .

CVSS v3 metric

CVSS v3 base score 8.2 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L.

EPSS exploit prediction

EPSS: 0.005 (37.7th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 38th percentile — 37.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-46510: held from 0.003 to 0.005.

EPSS over last 30 days · oldest: 0.003 · newest: 0.005 · change: +0.002

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-46510?
CVE-2026-46510 is a high-severity vulnerability in Kaspernj Form-Data-Objectizer, classified under Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution). CVSS score: 8.2/10. Published 2026-05-29.
How severe is CVE-2026-46510?
High severity. CVSS v3 base score is 8.2 out of 10.