{"id":"CVE-2026-48819","aliases":["GHSA-hhx9-57xq-r5rw"],"url":"https://o3.security/vulnerability/CVE-2026-48819","summary":"Hey API: `buildClientParams` template: prototype chain substitution via unknown `$<slot>___proto__` key","details":"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.","published":"2026-07-17T19:46:00.402Z","modified":"2026-08-12T03:51:18.808924364Z","cvss":{"score":4.8,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"@hey-api/openapi-ts","fixedVersion":"0.97.3"}],"fix":{"url":"https://github.com/hey-api/hey-api/commit/023909137a15eff9c0263d3bcd116140076b214f","label":"hey-api/hey-api@0239091"},"references":[{"type":"WEB","url":"https://github.com/hey-api/hey-api/releases/tag/%40hey-api%2Fopenapi-ts%400.97.3"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/48xxx/CVE-2026-48819.json"},{"type":"ADVISORY","url":"https://github.com/hey-api/hey-api/security/advisories/GHSA-hhx9-57xq-r5rw"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-48819"},{"type":"FIX","url":"https://github.com/hey-api/hey-api/commit/023909137a15eff9c0263d3bcd116140076b214f"},{"type":"FIX","url":"https://github.com/hey-api/hey-api/commit/da321a1529eb3c90d2109da870f514b915a60169"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:18.808924364Z"}}