CVE-2026-71869: Orval: Import-time RCE via array-items default -> zod module-level template literal
Summary
Orval's zod schema generation emits the array-items default value as a module-level template literal (export const …Default = <default>;) without escaping ${ or the backtick. A default of the form v${<code>}w injects a live JavaScript expression evaluated when the generated zod schema module is imported, executing attacker-controlled code at import — no request or function call needed. Verified on Orval 8.19.0; survives default OpenAPI validation.
Details
ts export const …Default = v${globalThis.ORVPWN()}w; // ${...} = arbitrary JS expression, runs at import
Malicious input: an array property (string items) with a default of v${<attacker JS>}w. ${...} permits any JS expression.
Note: this is one of several default-bearing positions that reach the same unescaped zod template-literal sink; a single fix (escape default values) closes all of them, and a CNA may choose to consolidate the related reports.
PoC
reproduce.sh (+ makespec.py) attached: generates the zod schema with default validation, bundles it, imports it, and shows a marker written at import. Verified on 8.19.0.
Impact
Code execution at import in any application that imports a zod schema module generated from an attacker-controlled or attacker-influenced OpenAPI description.
Suggested fix
Emit default values via a proper string-literal encoder (JSON.stringify, or escape backtick and ${ if a template literal must be used); never interpolate a spec value into a template literal. Apply to every default position. maintainer-report.txt makespec.pyreproduce.sh
Other sources
Orval generates type-safe JavaScript clients in TypeScript from OpenAPI v3 and Swagger v2 specifications. Prior to 8.21.0, a ${...} expression or backtick in an array item default is emitted into a module-level template literal emitted by zod schema generation without safe encoding. This permits attacker-controlled JavaScript to be evaluated when the generated zod schema module is imported, resulting in code execution in the developer, CI, test, or application environment. The affected code is packages/zod/src/index.ts function formatDefaultValue. This issue is fixed in version 8.21.0.
— MITRE
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
npm/orvalto a version that resolves this vulnerability.Fixed in 8.21.0 - Upgrade
Upgrade
orvalto a version that resolves this vulnerability.Fixed in 8.21.0 - Configuration
Update Orval so array-items `default` values are emitted via safe string-literal encoding (e.g., JSON.stringify, or escape backtick and `${` if using a template literal). This prevents `${...}` from being evaluated at module import time.
Orval (zod schema generation) packages/zod/src/index.ts function formatDefaultValue zod module-level template literal emission for default values (escaping of `${` and backticks) = Escape `${` sequence and backticks in default string values before inserting into export const …Default = `<default>`; do not emit attacker-controlled `${...}` as a live JS expression
Event History
Frequently Asked Questions
Who is exposed to this issue?
Users of Orval versions before 8.21.0 are exposed when they generate Zod schemas from an OpenAPI or Swagger specification containing a malicious array item default. The resulting risk applies wherever the generated schema module is imported, including developer, CI, test, or application environments.
What does an attacker need to exploit it?
An attacker needs control over, or the ability to influence, an API specification processed by the affected Orval Zod schema generator. The specification must include a ${...} expression or backtick in an array item default so that it is emitted unsafely into a module-level template literal.
When does code execution occur?
The attacker-controlled JavaScript is evaluated when the generated Zod schema module is imported. Generation alone is not described as the execution trigger; importing the generated module is.
How can this be remediated?
Upgrade Orval to version 8.21.0, which fixes the affected formatDefaultValue handling in packages/zod/src/index.ts. Until upgrading, avoid generating or importing Zod schema output from untrusted or unreviewed API specifications, especially specifications with array item defaults.