CVE-2026-48819

MEDIUM

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

Title source: cna
STIX 2.1

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.

References (4)

Core 4

Scores

CVSS v3 4.8
EPSS 0.0022
EPSS Percentile 12.8%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

CISA SSVC

Vulnrichment
Exploitation poc
Automatable no
Technical Impact partial

Details

CWE
CWE-1321
Status published
Products (1)
hey-api/openapi-ts < 0.97.3
Published Jul 17, 2026
Tracked Since Jul 18, 2026