Parse Server crash via deeply nested query condition operators

Impact

An unauthenticated attacker can crash the Parse Server process by sending a single request with deeply nested query condition operators. This terminates the server and denies service to all connected clients.

Patches

A depth limit for query condition operator nesting has been added via the requestComplexity.queryDepth server option. The option is disabled by default to avoid a breaking change. To mitigate, upgrade and set the option to a value appropriate for your app.

Workarounds

None.