GraphQL-core: Denial of service via quadratic complexity in the OverlappingFieldsCanBeMerged validation rule
The OverlappingFieldsCanBeMerged validation rule can be driven into quadratic — and in the worst case O(n²·m²) — running time by a small, highly compressible query. A single 364 KB document can occupy one CPU core for over five minutes during validation, before any resolver runs. Because the rule is part of specified_rules and therefore enabled by default, every GraphQL-core based server is affected at default settings.