apollo-compiler is a query-based compiler for the GraphQL query language. Prior to 1.27.0, a vulnerability in Apollo Compiler allowed queries with deeply nested and reused named fragments to be prohibitively expensive to validate. Named fragments were being processed once per fragment spread in some cases during query validation, leading to exponential resource usage when deeply nested and reused fragments were involved. This could lead to excessive resource consumption and denial of service in applications. This vulnerability is fixed in 1.27.0.

Affected: crates.io: apollo-compiler

# Impact

## Summary

A vulnerability in Apollo Compiler allowed queries with deeply nested and reused named fragments to be prohibitively expensive to validate. This could lead to excessive resource consumption and denial of service in applications.

## Details

Named fragments were being processed once per fragment spread in some cases during query validation, leading to exponential resource usage when deeply nested and reused fragments were involved.

## Fix/Mitigation

The validation logic has been updated to process each named fragment only once, preventing redundant traversal.

# Patches This has been remediated in `apollo-compiler` version 1.27.0.

# Workarounds No known direct workarounds exist.

## Acknowledgements We appreciate the efforts of the security community in identifying and improving the performance and security of query validation mechanisms.