mercurius has Uncaught Exception when using subscriptions

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.
The patch was released as v11.5.0 and v8.13.2.

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/228