CVE-2026-41016
Apache Airflow Providers SMTP: No certificate validation on SMTP STARTTLS connections in SMTP provider
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
5.9
Apache Airflow Providers SMTP: No certificate validation on SMTP STARTTLS connections in SMTP provider
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.
- Record
CVE-2026-41016- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N - Weakness
- CWE-295
- Updated
- 2026-11-02
EUVDEUVD-2026-26359
5.9
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.
- Record
EUVD-2026-26359- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-x8mh-94wc-33gv
5.9
apache-airflow-providers-smtp: No certificate validation on SMTP STARTTLS connections in SMTP provider
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.
- Record
GHSA-x8mh-94wc-33gv- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N - Weakness
- CWE-295
- Updated
- 2026-11-02
NVD
5.9
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.
- Record
CVE-2026-41016- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N - Weakness
- CWE-295
- Updated
- 2026-11-02
OSV
5.9
Apache Airflow Providers SMTP: No certificate validation on SMTP STARTTLS connections in SMTP provider
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.
- Record
CVE-2026-41016- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N - Weakness
- CWE-295
- Updated
- 2026-11-02
OSVGHSA-x8mh-94wc-33gv
5.9
apache-airflow-providers-smtp: No certificate validation on SMTP STARTTLS connections in SMTP provider
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.
- Record
GHSA-x8mh-94wc-33gv- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N - Weakness
- CWE-295
- Updated
- 2026-11-02
OSVPYSEC-2026-24
5.9
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.
- Record
PYSEC-2026-24- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N - Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
apache-airflow-providers-smtpPyPI |
2.0.0 up to 3.0.0 | 3.0.0 |
apache-airflow-providers-smtpPyPI |
2.0.0 up to 3.0.0, plus listed versions 2.0.12.0.1rc12.0.22.0.2rc12.0.3 Show 30 moreShow less2.0.3rc12.1.02.1.0rc12.1.12.1.1rc12.1.22.1.2rc12.2.02.2.0rc12.2.12.2.1rc12.3.02.3.0rc12.3.12.3.1rc12.3.22.3.2rc12.4.02.4.0rc12.4.12.4.1rc12.4.22.4.2rc12.4.32.4.3rc12.4.42.4.4rc12.4.52.4.5rc13.0.0rc1 |
3.0.0 |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-41016 is a medium vulnerability (CVSS 5.9) in Apache Airflow, published April 30, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.27%, the 19th percentile. Fixed in apache-airflow-providers-smtp 3.0.0.
References
github.com/apache/airflow/pull/65346
lists.apache.org/thread/gb202qy5r31bgdd3d51d7s5o1jh40kc4
nvd.nist.gov/vuln/detail/CVE-2026-41016
github.com/pypa/advisory-database/tree/main/vulns/apache-airflow-providers-smtp/PYSEC-2026-24.yaml
github.com/advisories/GHSA-x8mh-94wc-33gv
pypi.python.org
github.com/CVEProject/cvelistV5/tree/main/cves/2026/41xxx/CVE-2026-41016.json
github.com/apache/airflow