# Apollo Server schema validation bypass on WebSocket subscriptions

Source: https://junglewise.ai/threats/apollo-server-schema-validation-bypass-on-websocket-subscriptions-f355648d  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2020-06-05. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

Severity: info · Published 2020-06-05

Apollo Server is a GraphQL implementation used by developers to build APIs. When subscriptions are enabled (the default), schema validation rules—including introspection restrictions meant to hide sensitive field and type names—are not applied to the WebSocket subscription endpoint. An attacker can query this endpoint to discover internal schema details, field names, or descriptions that developers intended to keep private, potentially exposing secrets or aiding further attacks.

Technologies: [apollo-server (npm)](https://junglewise.ai/threats/technologies/apollo-server), [apollo-server-core (npm)](https://junglewise.ai/threats/technologies/apollo-server-core). Vendors: [npm](https://junglewise.ai/threats/vendors/npm).

## Quick answers

**Is This vulnerability exploited in the wild?** No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.

**How severe is This vulnerability?** Informational severity, published 5 June 2020.

**Which products and versions are affected?** apollo-server (npm) SEMVER:introduced=0,fixed=2.14.2; apollo-server-azure-functions (npm) SEMVER:introduced=0,fixed=2.14.2; apollo-server-cache-memcached (npm) SEMVER:introduced=0,fixed=2.14.2; apollo-server-cloud-functions (npm) SEMVER:introduced=0,fixed=2.14.2; and 8 more.

**Is there a fix for This vulnerability?** Yes. apollo-server (npm): upgrade to 2.14.2 or later; apollo-server-azure-functions (npm): upgrade to 2.14.2 or later; apollo-server-cache-memcached (npm): upgrade to 2.14.2 or later; apollo-server-cloud-functions (npm): upgrade to 2.14.2 or later; apollo-server-cloudflare (npm): upgrade to 2.14.2 or later; apollo-server-core (npm): upgrade to 2.14.2 or later; apollo-server-express (npm): upgrade to 2.14.2 or later; apollo-server-fastify (npm): upgrade to 2.14.2 or later; apollo-server-hapi (npm): upgrade to 2.14.2 or later; apollo-server-koa (npm): upgrade to 2.14.2 or later; apollo-server-lambda (npm): upgrade to 2.14.2 or later; apollo-server-micro (npm): upgrade to 2.14.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is This vulnerability attacked?** It is attacked over the network.

**Am I affected?** Check whether you run apollo-server (npm), apollo-server-azure-functions (npm), apollo-server-cache-memcached (npm) or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- apollo-server (npm): upgrade to 2.14.2 or later

  ```sh
  npm install apollo-server@2.14.2
  ```

- apollo-server-azure-functions (npm): upgrade to 2.14.2 or later

  ```sh
  npm install apollo-server-azure-functions@2.14.2
  ```

- apollo-server-cache-memcached (npm): upgrade to 2.14.2 or later

  ```sh
  npm install apollo-server-cache-memcached@2.14.2
  ```

- apollo-server-cloud-functions (npm): upgrade to 2.14.2 or later

  ```sh
  npm install apollo-server-cloud-functions@2.14.2
  ```

- apollo-server-cloudflare (npm): upgrade to 2.14.2 or later

  ```sh
  npm install apollo-server-cloudflare@2.14.2
  ```

- apollo-server-core (npm): upgrade to 2.14.2 or later

  ```sh
  npm install apollo-server-core@2.14.2
  ```

- apollo-server-express (npm): upgrade to 2.14.2 or later

  ```sh
  npm install apollo-server-express@2.14.2
  ```

- apollo-server-fastify (npm): upgrade to 2.14.2 or later

  ```sh
  npm install apollo-server-fastify@2.14.2
  ```

- apollo-server-hapi (npm): upgrade to 2.14.2 or later

  ```sh
  npm install apollo-server-hapi@2.14.2
  ```

- apollo-server-koa (npm): upgrade to 2.14.2 or later

  ```sh
  npm install apollo-server-koa@2.14.2
  ```

- apollo-server-lambda (npm): upgrade to 2.14.2 or later

  ```sh
  npm install apollo-server-lambda@2.14.2
  ```

- apollo-server-micro (npm): upgrade to 2.14.2 or later

  ```sh
  npm install apollo-server-micro@2.14.2
  ```


## Technical details

The vulnerability is a validation rule bypass affecting the WebSocket subscription server in Apollo Server. When ApolloServer is instantiated with subscriptions enabled (default behavior) and custom validationRules or the internal NoIntrospection rule configured, those rules are not passed to the SubscriptionServer instance. This allows introspection queries on the WebSocket endpoint even when disabled elsewhere, and permits other user-defined validation rules to be circumvented. The attack requires network access to the WebSocket subscriptions endpoint. The root cause is that validationRules are enforced on the main HTTP pipeline but omitted when invoking SubscriptionServer.create(). The fix ensures validation rules are consistently applied across all transports. Patched in versions 2.14.2 and higher.

## Affected products

- Apollo apollo-server 2.0.0 to 2.14.1
- Apollo apollo-server-core 2.0.0 to 2.14.1
- Apollo apollo-server-express 2.0.0 to 2.14.1
- Apollo apollo-server-lambda 2.0.0 to 2.14.1
- Apollo apollo-server-koa 2.0.0 to 2.14.1
- Apollo apollo-server-azure-functions 2.0.0 to 2.14.1
- Apollo apollo-server-cache-memcached 2.0.0 to 2.14.1
- Apollo apollo-server-cloud-functions 2.0.0 to 2.14.1
- Apollo apollo-server-cloudflare 2.0.0 to 2.14.1
- Apollo apollo-server-fastify 2.0.0 to 2.14.1
- Apollo apollo-server-hapi 2.0.0 to 2.14.1
- Apollo apollo-server-micro 2.0.0 to 2.14.1

## Timeline

- 2020-06-05: disclosed: Advisory published
- 2020-06-05: patched: Patch released in versions 2.14.2 and higher

## References

- [https://github.com/apollographql/apollo-server/security/advisories/GHSA-w42g-7vfc-xf37](https://github.com/apollographql/apollo-server/security/advisories/GHSA-w42g-7vfc-xf37)
- [https://github.com/apollographql/apollo-server/commit/e2e816316f5c28a03de2ee1589edb2b10c358114](https://github.com/apollographql/apollo-server/commit/e2e816316f5c28a03de2ee1589edb2b10c358114)

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- [Apollo Server sensitive information exposure in logging](https://junglewise.ai/threats/apollo-server-sensitive-information-exposure-in-logging-64cb113a)
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