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.
References5
- github.com/hey-api/hey-api/commit/023909137a15eff9c0263d3bcd116…
- github.com/hey-api/hey-api/commit/da321a1529eb3c90d2109da870f51…
- github.com/hey-api/hey-api/releases/tag/%40hey-api%2Fopenapi-ts…
- github.com/hey-api/hey-api/security/advisories/GHSA-hhx9-57xq-r…
- github.com/hey-api/hey-api/security/advisories/GHSA-hhx9-57xq-r…
Metrics
- CVSS 3.1
-
4.8
MEDIUM
Score source: CNA
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N - EPSS — exploit probability
- 0% percentile: 20 · as of 14 November 2026
- CWE
- CWE-1321
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.