Impact Summary A vulnerability in Apollo Router allowed queries with deeply nested and reused named fragments to be prohibitively expensive to query plan, specifically during named fragment expansion. This could lead to excessive resource consumption and denial of service. Details Named fragments were being expanded once per fragment spread during query planning, leading to exponential resource usage when deeply nested and reused fragments were involved. Fix/Mitigation A new Query Fragment Expansion Limit metric has been introduced: – This metric computes the number of selections a query would have if its fragment spreads were fully expanded. – The metric is checked against a limit to prevent excessive computation. Patches This has been remediated in apollo-router versions 1.61.2 and 2.1.1. Workarounds The only known workaround is "Safelisting" or "Safelisting with IDs only" per Safelisting with Persisted Queries – Apollo GraphQL Docs. References Query Planning Documentation Acknowledgements We appreciate the efforts of the security community in identifying and improving the performance and security of query planning…Read More