Orval: RCE via OpenAPI path -> unescaped request-URL template literal (backtick breakout)

Summary

Orval emits the OpenAPI path into the generated request URL as a TEMPLATE LITERAL (`/users/...`) without escaping the backtick character. A path containing a backtick closes the template literal and injects a concatenation expression that is evaluated when the generated URL/request/key function is called, executing attacker-controlled code. Affects the axios, fetch, react-query, and swr clients. Verified on Orval 8.19.0; survives Orval's default OpenAPI validation.

Details

// generated URL builder (fetch client)
return `/users/` + (globalThis.X = require("fs").writeFileSync("/marker","pwned")) + `/list`;

The backtick in the path terminates the `...` literal; + (<code>) + runs as a live expression; a trailing backtick reopens a template literal so the file stays valid. The code runs whenever the generated request function, URL builder, or query-key function is called.

This is distinct from Orval's four published CVEs: CVE-2026-22785 (summary -> MCP server), CVE-2026-23947 / CVE-2026-25141 (x-enumDescriptions), and CVE-2026-24132 (const -> mock files). This is a different field (the route path) and a different sink (the request-URL template literal), which those advisories and their fixes do not cover.

PoC

reproduce.sh (+ make_spec.py) attached: generates a fetch client with default validation, bundles it, calls the generated functions, and shows a marker file written. Verified on 8.19.0.

Impact

Code execution in any environment that calls a client generated from an attacker-controlled or attacker-influenced OpenAPI description (developer, CI, or the running application).

Suggested fix

Escape the path before emitting it into the URL template literal (escape backtick and ${, or build the URL with an encoder that treats the path as data), and validate path characters.