CVE-2026-48819

Medium

Description

Hey API is an ecosystem for turning API specifications into production-ready code. Prior to 0.97.3, dist/clients/core/params.ts ships a runtime template copied into generated SDKs as params.gen.ts, and buildClientParams writes unknown slot-prefixed keys such as $body_, $headers_, $path_, and $query_ directly to the corresponding slot, allowing $query___proto__ alongside a legitimate q field to set params.query through params["query"]["__proto__"] = value, call Object.setPrototypeOf(params.query, value), and expose inherited attacker-controlled keys during for..in iteration. This issue is fixed in version 0.97.3.

SeverityMedium

CVSS4.8

Exploit probability—

Product@hey-api/openapi-ts

PublishedJul 17, 2026

First seenJul 17, 2026

Weakness typeCWE-1321Prototype pollution

How to fix

Update

@hey-api/openapi-ts0.97.3 or later

Affected products

Product	Affected versions	Fixed in
@hey-api/openapi-tsnpm	v < 0.97.3	0.97.3

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