A flaw in Elasticsearch allows an authenticated user with the privileges required to invoke the simulate pipeline API endpoint (https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-ingest-simulate) to submit a request that causes a self-referential data structure to be created. When a specific internal component later processes that structure, the operation recurses without bound and raises a fatal error that is not handled by the surrounding execution path, terminating the affected node process and resulting in a denial of service.