CVE-2026-49267: Apache Airflow: No certificate validation on SMTP STARTTLS connections

Apache Airflow's EmailOperator and the underlying airflow.utils.email helpers established SMTP STARTTLS connections without verifying the remote certificate when the deployment used [email] smtpstarttls=True without [email] smtpssl. An attacker positioned between the worker and the configured SMTP server (network MITM — typical hostile-network attack-surface for environments where the SMTP relay sits outside the worker's trust boundary) could present a self-signed certificate, have the worker complete the STARTTLS handshake silently, and capture the SMTP AUTH credentials and message contents the worker forwarded.

This CVE covers the core apache-airflow side of the same root cause already covered for the SMTP provider by CVE-2026-41016 (published 2026-04-27, covering apache-airflow-providers-smtp). Users who already applied the SMTP-provider fix from CVE-2026-41016 should additionally upgrade apache-airflow to 3.2.2 or later to cover the core-side path through airflow.utils.email. Affects deployments configured with smtpstarttls=True and smtpssl=False where the SMTP relay is reachable across a less-trusted network segment than the worker.

Users are advised to upgrade to apache-airflow 3.2.2 or later.