CVE-2026-45360: Apache Airflow: Arbitrary import in custom deadline-reference deserialization

[Rahul Vats <rahulvats () apache org>]

Severity: high 

Affected versions:

- Apache Airflow (apache-airflow) before 3.2.2

Description:

Apache Airflow's scheduler-side deadline-reference decoder (`SerializedCustomReference.deserialize_reference`) imported 
and dispatched arbitrary class paths drawn from DAG-author-controlled serialized state without an allowlist or 
plugin-registry gate. A DAG author whose code reaches the scheduler — the default on single-host deployments where the 
DAG bundle is importable from the scheduler process — could embed a custom `DeadlineReference` whose serialized form 
named an attacker-controlled module path, causing the scheduler to `import_string(...)` and instantiate that class with 
a live SQLAlchemy session attached. Affects deployments where DAG-author code is less trusted than the scheduler 
process. Users are advised to upgrade to `apache-airflow` 3.2.2 or later.

Credit:

Jarek Potiuk (remediation developer)

References:

https://github.com/apache/airflow/pull/66737
https://airflow.apache.org/
https://www.cve.org/CVERecord?id=CVE-2026-45360