Apollo Router Query Planner Vulnerable to Excessive Resource Consumption via Named Fragment Expansion

The Apollo Router Core is a configurable, high-performance graph router written in Rust to run a federated supergraph that uses Apollo Federation 2. Prior to 1.61.2 and 2.1.1, 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. 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. This could lead to excessive resource consumption and denial of service. This has been remediated in apollo-router versions 1.61.2 and 2.1.1.