Orval: RCE via servers[].url -> unescaped request-URL template literal (with getBaseUrlFromSpecification)

Summary

When Orval is configured with output.baseUrl.getBaseUrlFromSpecification: true, it bakes the spec's servers[0].url into the generated request URL as a template literal without escaping the backtick. A server URL containing a backtick closes the template literal and injects a concatenation expression evaluated when the generated URL/request function is called, executing attacker-controlled code. Verified on Orval 8.19.0 (fetch client); survives default OpenAPI validation.

Details

return `http://api.x/` + (globalThis.X = require("fs").writeFileSync("/marker","pwned")) + `/v1/u`;

Prerequisite: the documented getBaseUrlFromSpecification: true option (takes the base URL from the OpenAPI servers block). This is the same output sink as the route-path case (request-URL template literal) reached via the server url field. Distinct from Orval's published CVEs (CVE-2026-22785 summary/MCP, CVE-2026-23947 / CVE-2026-25141 x-enumDescriptions, CVE-2026-24132 const/mock).

PoC

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

Impact

With that option enabled, code execution in any environment that calls a client generated from an attacker-controlled or attacker-influenced OpenAPI description.

Suggested fix

Escape the server URL before emitting it into the URL template literal (escape backtick and ${), or build the base URL with an encoder that treats it as data; validate the URL.
maintainer-report.txt
make_spec.py
reproduce.sh