CVE-2026-59148

Mockoon provides way to design and run mock APIs. Prior to 9.7.0, Mockoon's admin API in commons-server/src/libs/server/admin-api.ts is mounted on the same Express listener as user-defined mock routes, enabled by default in shipped runtimes, serves Access-Control-Allow-Origin: * with write methods allowed, and has no authentication. Any unauthenticated caller who can reach the mock server port can read MOCKOON_* environment variables, write arbitrary process environment variables through /mockoon-admin/env-vars, rewrite mock route bodies, statuses, and headers through PUT /mockoon-admin/environment, read transaction logs and SSE streams, and purge state. This issue is fixed in version 9.7.0.

Mockoon provides way to design and run mock APIs. Prior to 9.7.0, Mockoon's admin API in commons-server/src/libs/server/admin-api.ts is mounted on the same Express listener as user-defined mock routes, enabled by default in shipped runtimes, serves Access-Control-Allow-Origin: * with write methods allowed, and has no authentication. Any unauthenticated caller who can reach the mock server port can read MOCKOON_* environment variables, write arbitrary process environment variables through /mockoon-admin/env-vars, rewrite mock route bodies, statuses, and headers through PUT /mockoon-admin/environment, read transaction logs and SSE streams, and purge state. This issue is fixed in version 9.7.0.

Summary

Mockoon's admin API (commons-server/src/libs/server/admin-api.ts) is mounted on the same Express listener as the user-defined mock routes, enabled by default in every shipped runtime (commons-server, CLI, serverless), serves Access-Control-Allow-Origin: * on every endpoint with all HTTP methods allowed including PUT/POST/PATCH/DELETE/PURGE and Content-Type in Access-Control-Allow-Headers, and has zero authentication of any kind (no token, no shared secret, no MOCKOON_ADMIN_TOKEN env var — searched the repo, returns zero hits).

Any unauthenticated caller who can reach the mock server's port (default 0.0.0.0:3000) can:

• Read every MOCKOON_* env var used by the operator as secret material in templates (getEnvVar helper).
• Write arbitrary process env vars (no prefix check on the WRITE path) — poison operator's MOCKOON_API_KEY, MOCKOON_JWT_SECRET, …, or write process-level vars like AWS_SECRET_ACCESS_KEY that the surrounding runtime consumes.
• Rewrite every mock route's body / status / headers in-runtime via PUT /mockoon-admin/environment — downstream consumers (frontend dev-server, CI test suite, integration partner) receive attacker-controlled responses and headers including Set-Cookie, Location, Content-Security-Policy, etc.
• Read transaction logs / SSE stream (consumer's request bodies + auth headers in clear).
• Read/write global template vars; purge state / data buckets / logs.

Because of the wildcard CORS reply, the attack also lands cross-origin from a browser: a developer who runs mockoon-cli start ... locally and visits a malicious website gets their mock state hijacked.

Details

Root cause

packages/commons-server/src/libs/server/server.ts:127:

private options: ServerOptions = {
  ...,
  enableAdminApi: true,        // ← default on
};

packages/cli/src/commands/start.ts:200:

enableAdminApi: !userFlags['disable-admin-api'],   // default true unless --disable-admin-api passed

packages/serverless/src/libs/serverless.ts:21:

enableAdminApi: true,          // ← default on, no flag to disable in the constructor

packages/commons-server/src/libs/server/admin-api.ts:63-74 (permissive CORS on every admin endpoint):

app.use(`${adminApiPrefix}*`, (req, res, next) => {
  res.setHeaders(
    new Headers({
      'Access-Control-Allow-Origin': '*',
      'Access-Control-Allow-Methods':
        'GET,POST,PUT,PATCH,DELETE,HEAD,OPTIONS',
      'Access-Control-Allow-Headers':
        'Content-Type, Origin, Accept, Authorization, Content-Length, X-Requested-With'
    })
  );
  next();
});

packages/commons-server/src/libs/server/admin-api.ts:151-166 (no auth, no prefix check on WRITE):

const setEnvVarHandler = (req, res) => {
  try {
    const { key, value } = req.body;
    if (key !== undefined && value !== undefined) {
      process.env[key] = value;                            // ← any process env, any value
      res.send({ message: `Environment variable '${key}' has been set to '${value}'` });
    } else {
      throw new Error('Key or value missing from request');
    }
  } catch (_error) {
    res.status(400).send({ message: 'Invalid request' });
  }
};

packages/commons-server/src/libs/server/admin-api.ts:373-393 (the most impactful — runtime mock rewrite):

app.put(`${adminApiPrefix}/environment`, (req, res) => {
  try {
    const environment: Environment = EnvironmentSchema.validate(req.body).value;
    if (!environment) {
      res.status(400).send({ message: 'Invalid environment format' });
      return;
    }
    updateEnvironment(environment);                        // ← runtime mutation of every route response
    res.send({ message: 'Environment updated' });
  } catch (_error) {
    res.status(400).send({ message: 'Invalid environment format' });
…

Mockoon provides way to design and run mock APIs. Prior to 9.7.0, Mockoon's admin API in commons-server/src/libs/server/admin-api.ts is mounted on the same Express listener as user-defined mock routes, enabled by default in shipped runtimes, serves Access-Control-Allow-Origin: * with write methods allowed, and has no authentication. Any unauthenticated caller who can reach the mock server port can read MOCKOON_* environment variables, write arbitrary process environment variables through /mockoon-admin/env-vars, rewrite mock route bodies, statuses, and headers through PUT /mockoon-admin/environment, read transaction logs and SSE streams, and purge state. This issue is fixed in version 9.7.0.

Mockoon provides way to design and run mock APIs. Prior to 9.7.0, Mockoon's admin API in commons-server/src/libs/server/admin-api.ts is mounted on the same Express listener as user-defined mock routes, enabled by default in shipped runtimes, serves Access-Control-Allow-Origin: * with write methods allowed, and has no authentication. Any unauthenticated caller who can reach the mock server port can read MOCKOON_* environment variables, write arbitrary process environment variables through /mockoon-admin/env-vars, rewrite mock route bodies, statuses, and headers through PUT /mockoon-admin/environment, read transaction logs and SSE streams, and purge state. This issue is fixed in version 9.7.0.

Summary

Mockoon's admin API (commons-server/src/libs/server/admin-api.ts) is mounted on the same Express listener as the user-defined mock routes, enabled by default in every shipped runtime (commons-server, CLI, serverless), serves Access-Control-Allow-Origin: * on every endpoint with all HTTP methods allowed including PUT/POST/PATCH/DELETE/PURGE and Content-Type in Access-Control-Allow-Headers, and has zero authentication of any kind (no token, no shared secret, no MOCKOON_ADMIN_TOKEN env var — searched the repo, returns zero hits).

Any unauthenticated caller who can reach the mock server's port (default 0.0.0.0:3000) can:

• Read every MOCKOON_* env var used by the operator as secret material in templates (getEnvVar helper).
• Write arbitrary process env vars (no prefix check on the WRITE path) — poison operator's MOCKOON_API_KEY, MOCKOON_JWT_SECRET, …, or write process-level vars like AWS_SECRET_ACCESS_KEY that the surrounding runtime consumes.
• Rewrite every mock route's body / status / headers in-runtime via PUT /mockoon-admin/environment — downstream consumers (frontend dev-server, CI test suite, integration partner) receive attacker-controlled responses and headers including Set-Cookie, Location, Content-Security-Policy, etc.
• Read transaction logs / SSE stream (consumer's request bodies + auth headers in clear).
• Read/write global template vars; purge state / data buckets / logs.

Because of the wildcard CORS reply, the attack also lands cross-origin from a browser: a developer who runs mockoon-cli start ... locally and visits a malicious website gets their mock state hijacked.

Details

Root cause

packages/commons-server/src/libs/server/server.ts:127:

private options: ServerOptions = {
  ...,
  enableAdminApi: true,        // ← default on
};

packages/cli/src/commands/start.ts:200:

enableAdminApi: !userFlags['disable-admin-api'],   // default true unless --disable-admin-api passed

packages/serverless/src/libs/serverless.ts:21:

enableAdminApi: true,          // ← default on, no flag to disable in the constructor

packages/commons-server/src/libs/server/admin-api.ts:63-74 (permissive CORS on every admin endpoint):

app.use(`${adminApiPrefix}*`, (req, res, next) => {
  res.setHeaders(
    new Headers({
      'Access-Control-Allow-Origin': '*',
      'Access-Control-Allow-Methods':
        'GET,POST,PUT,PATCH,DELETE,HEAD,OPTIONS',
      'Access-Control-Allow-Headers':
        'Content-Type, Origin, Accept, Authorization, Content-Length, X-Requested-With'
    })
  );
  next();
});

packages/commons-server/src/libs/server/admin-api.ts:151-166 (no auth, no prefix check on WRITE):

const setEnvVarHandler = (req, res) => {
  try {
    const { key, value } = req.body;
    if (key !== undefined && value !== undefined) {
      process.env[key] = value;                            // ← any process env, any value
      res.send({ message: `Environment variable '${key}' has been set to '${value}'` });
    } else {
      throw new Error('Key or value missing from request');
    }
  } catch (_error) {
    res.status(400).send({ message: 'Invalid request' });
  }
};

packages/commons-server/src/libs/server/admin-api.ts:373-393 (the most impactful — runtime mock rewrite):

app.put(`${adminApiPrefix}/environment`, (req, res) => {
  try {
    const environment: Environment = EnvironmentSchema.validate(req.body).value;
    if (!environment) {
      res.status(400).send({ message: 'Invalid environment format' });
      return;
    }
    updateEnvironment(environment);                        // ← runtime mutation of every route response
    res.send({ message: 'Environment updated' });
  } catch (_error) {
    res.status(400).send({ message: 'Invalid environment format' });
…