The webonyx/graphql-php library contains an unbounded recursion vulnerability in its parser that can cause a stack overflow and crash the PHP process. The recursive descent parser lacks any recursion depth limit or token counting, leading to exhaustion of the C stack and a segmentation fault (SIGSEGV) when processing deeply nested crafted GraphQL queries. This results in the termination of the PHP FPM/CLI worker process handling the request, dropping all concurrent requests without error or logs. The smallest crashing payload is approximately 74 KB, which is below typical HTTP body size limits. This issue affects versions prior to 15.32.3 and is fixed in 15.32.3.