Apache Airflow versions prior to 3.4.0 did not reject reserved serialization keys inside a Dag run's configuration. This flaw allowed users authorized to trigger a Dag with a deadline alert and asynchronous callback to pass a crafted configuration that could cause the scheduler to crash repeatedly or cause improper object reconstruction inside the Triggerer after a missed deadline. Upgrading to Apache Airflow 3.4.0 or later resolves this issue.