CVE-2026-67260: Apache Airflow scheduler unsafely deserializes human-in-the-loop task next_kwargs

Apache Airflow 3.3.0 moved human-in-the-loop tasks from the triggerer to a new awaiting_input task state swept by the scheduler. That sweep deserializes the task instance’s next_kwargs without an allow-list, so a Dag author — who controls that value through the task execution API — can cause an arbitrary module import and object instantiation inside the scheduler process, or terminate the scheduler job. No non-default configuration is required: the sweep runs unconditionally every 15 seconds, and the default allowed_deserialization_classes setting does not cover this code path. Versions before 3.3.0 are not affected, because human-in-the-loop tasks deferred onto the triggerer instead. This is a different code path from CVE-2026-58076, which covers the same unguarded exception-node deserialization reached elsewhere — deployments that applied that fix must upgrade for this issue as well. Users are advised to upgrade to apache-airflow 3.3.1 or later.