---
id: CVE-2026-41016
aliases:
  - GHSA-x8mh-94wc-33gv
  - PYSEC-2026-24
title: >-
  apache-airflow-providers-smtp: No certificate validation on SMTP STARTTLS
  connections in SMTP provider
summary: >-
  apache-airflow-providers-smtp: No certificate validation on SMTP STARTTLS
  connections in SMTP provider
severity: medium
cvss: 5.9
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N'
vendor: apache-airflow-providers-smtp
product: apache-airflow-providers-smtp
ecosystem: pip
affected:
  - 'apache-airflow-providers-smtp >= 2.0.0, < 3.0.0'
patched:
  - apache-airflow-providers-smtp 3.0.0
published: '2026-04-30'
updated: '2026-09-10'
sourceUpdated: '2026-09-10T03:51:03.971751299Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-x8mh-94wc-33gv'
references:
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-41016'
  - url: 'https://github.com/apache/airflow/pull/65346'
  - url: 'https://github.com/apache/airflow'
  - url: >-
      https://github.com/pypa/advisory-database/tree/main/vulns/apache-airflow-providers-smtp/PYSEC-2026-24.yaml
  - url: 'https://lists.apache.org/thread/gb202qy5r31bgdd3d51d7s5o1jh40kc4'
tags:
  - osv
  - pip
epss: 0.00268
epssPercentile: 0.1918
ingestedAt: '2026-09-12T03:13:01.739Z'
---

## Overview

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 packages

- `apache-airflow-providers-smtp >= 2.0.0, < 3.0.0`

## Remediation

Upgrade to a patched release:

- `apache-airflow-providers-smtp 3.0.0`