CVE-2026-46510 Prototype pollution in form-data-objectizer via bracket-notation form keys
Prototype pollution in form-data-objectizer allows attackers to mutate Object.prototype via crafted form keys, potentially leading to code execution.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-46510?
CVE-2026-46510 is a high-severity code injection vulnerability in kaspernj form-data-objectizer, published on 29 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-1321
Which versions are affected by CVE-2026-46510?
2 open source packages ship an affected version, including form-data-objectizer.
| Package | Affected | Fixed in |
|---|---|---|
form-data-objectizer npm | All versions | 1.0.1 |
form-data-objectizer npm | All versions | 1.0.1 |
How do I fix CVE-2026-46510?
Upgrade form-data-objectizer to 1.0.1 or later.
Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.
Is CVE-2026-46510 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-46510 exists.
Sources
Also known as GHSA-m2hg-wjq3-28wq.