CVE-2026-41016 Apache Airflow Providers SMTP: No certificate validation on SMTP STARTTLS connections in SMTP provider
Man-in-the-middle attackers can capture SMTP credentials due to missing certificate validation in Apache Airflow's SMTP provider.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-41016?
CVE-2026-41016 is a medium-severity vulnerability in Apache Airflow, published on 30 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-295
Which versions are affected by CVE-2026-41016?
3 open source packages ship an affected version, including apache-airflow-providers-smtp. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
apache-airflow-providers-smtp PyPI | From 2.0.0 | 3.0.0 |
apache-airflow-providers-smtp PyPI | From 2.0.0 | 3.0.0 |
apache-airflow-providers-smtp PyPI | From 2.0.0 | 3.0.0 |
Products include Apache Airflow.
How do I fix CVE-2026-41016?
Upgrade apache-airflow-providers-smtp to 3.0.0 or later.
Is CVE-2026-41016 being exploited?
There is no known exploitation of CVE-2026-41016 in the wild and no public exploit code.
Other vulnerabilities in Apache Airflow
- CVE-2020-13927 Apache Airflow's Experimental API Authentication Bypass
- CVE-2020-11978 Apache Airflow Command Injection
- CVE-2026-33264 Apache Airflow: DAG author RCE on webserver via unrestricted import_string() in BaseSerialization.deserialize()
- CVE-2023-25754 Apache Airflow: Privilege escalation using airflow logs
- CVE-2023-22884 Apache Airflow, Apache Airflow MySQL Provider: Arbitrary file read via MySQL provider in Apache Airflow
Sources
Also known as CLEANSTART-2026-ZG20439, ECHO-0c21-09c6-a700, GHSA-x8mh-94wc-33gv, MINI-382h-6gh3-m92q, MINI-9xpc-q8vq-2qch, PYSEC-2026-24.