CVE-2026-48819
Hey API: `buildClientParams` template: prototype chain substitution via unknown `$<slot>___proto__` key
- State
- Published
- Severity
- 4.8 Medium
- Published
- Jul 17, 2026
- Updated
- Jul 20, 2026
- Reserved
- May 22, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 4.8 Medium | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N | GitHub_M |
Weaknesses
- CWE-1321 Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
Affected Products
| Product | Versions |
|---|---|
openapi-tshey-api |
|
References
- https://github.com/hey-api/hey-api/security/advisories/GHSA-hhx9-57xq-r5rw
- https://github.com/hey-api/hey-api/commit/023909137a15eff9c0263d3bcd116140076b214f
- https://github.com/hey-api/hey-api/commit/da321a1529eb3c90d2109da870f514b915a60169
- https://github.com/hey-api/hey-api/releases/tag/%40hey-api%2Fopenapi-ts%400.97.3
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