### Impact

Any users of Mercurius until version v11.5.0 are subjected to a denial of service attack by sending a malformed packet over WebSocket to `/graphql`.

### Patches

This was patched in https://github.com/mercurius-js/mercurius/pull/940.

### Workarounds

Disable subscriptions.

### References

Reported publicly as https://github.com/mercurius-js/mercurius/issues/939.
The same problem was solved in https://github.com/fastify/fastify-websocket/pull/228Read More