CVE-2026-48819

Hey API: `buildClientParams` template: prototype chain substitution via unknown `$<slot>___proto__` key

Published Jul 17, 2026 CVSS 3.1 · 4.8 Medium EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-hhx9-57xq-r5rw @hey-api/openapi-ts's `buildClientParams` template: prototype chain substitution via unknown `$<slot>___proto__` key
History
Type Values Removed Values Added
First Time appeared Hey-api
Hey-api openapi-ts
Vendors & Products Hey-api
Hey-api openapi-ts
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
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 $query___proto__ alongside a legitimate q field to set params.query through params["query"]["__proto__"] = value, call Object.setPrototypeOf(params.query, value), and expose inherited attacker-controlled keys during for..in iteration. This issue is fixed in version 0.97.3.
Title Hey API: `buildClientParams` template: prototype chain substitution via unknown `$<slot>___proto__` key
Weaknesses CWE-1321
References
Metrics cvssV3_1

{'score': 4.8, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Jul 20, 2026, 4:24 PM
Reserved
May 22, 2026, 8:57 PM
Status
Deferred
Published
Jul 17, 2026, 8:17 PM
Modified
Oct 24, 2026, 8:10 PM