🔐 CVE Alert

CVE-2026-48819

MEDIUM 4.8

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

CVSS Score
4.8
EPSS Score
0.0%
EPSS Percentile
0th

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.

CWE CWE-1321
Vendor hey-api
Product openapi-ts
Published Jul 17, 2026
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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

Affected Versions

hey-api / openapi-ts
< 0.97.3

References

NVD ↗ CVE.org ↗ EPSS Data ↗
github.com: https://github.com/hey-api/hey-api/security/advisories/GHSA-hhx9-57xq-r5rw github.com: https://github.com/hey-api/hey-api/commit/023909137a15eff9c0263d3bcd116140076b214f github.com: https://github.com/hey-api/hey-api/commit/da321a1529eb3c90d2109da870f514b915a60169 github.com: https://github.com/hey-api/hey-api/releases/tag/%40hey-api%2Fopenapi-ts%400.97.3