Intel

AIKIDO-2026-10450

z-schema is vulnerable to Prototype Pollution

Prototype Pollution Pre-CVE
Found by Aikido Intel before public disclosure or CVE publication.
Published Apr 1, 2026

60

Medium Risk

This Affects:

JSz-schema
3.0.0 - 12.0.4
Fixed in 12.0.5
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TL;DR

Affected versions of z-schema are vulnerable to prototype pollution due to unsafe handling of user-controlled schema properties during schema compilation. The implementation allows special property names such as __proto__, constructor, or prototype to be assigned directly onto internal objects without validation. An attacker can supply a crafted schema containing these keys, resulting in modification of Object.prototype and pollution of subsequently created objects.

Who does this affect?

You are affected if you are using a version that falls within the vulnerable range.

Background info

z-schema is vulnerable to Prototype Pollution in versions 3.0.0 - 12.0.4.

How to fix this

Upgrade the z-schema library to the patch version.

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