CVE-2026-41016: Apache Airflow

Medium severity, CVSS 5.9. EPSS: 0.3% chance of exploitation in the next 30 days.

Apache Airflow's SMTP provider `SmtpHook` called Python's `smtplib.SMTP.starttls()` without an SSL context, so no certificate validation was performed on the TLS upgrade. A man-in-the-middle between the Airflow worker and the SMTP server could present a self-signed certificate, complete the STARTTLS upgrade, and capture the SMTP credentials sent during the subsequent `login()` call. Users are advised to upgrade to the `apache-airflow-providers-smtp` version that contains the fix.

Affected products

• Apache Airflow: from 2.0.0, before 3.0.0 (fixed in 3.0.0)

Published 2026-04-30. Last modified 2026-06-17.