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CVE-2026-41016

Apache Airflow Providers SMTP: No certificate validation on SMTP STARTTLS connections in SMTP provider

5.9 MediumFix available

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

0.27%Up 0.3 points since Apr 30, 2026
90%50%10%1%

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 MediumCVSS: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 MediumCVSS: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 MediumCVSS: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 MediumCVSS: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 MediumCVSS: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 MediumCVSS: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 MediumCVSS: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

Affected packages
PackageAffectedFixed
apache-airflow-providers-smtp
PyPI
2.0.0 up to 3.0.0
3.0.0
apache-airflow-providers-smtp
PyPI
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 less
2.0.3rc12.1.02.1.0rc12.1.12.1.1rc12.1.22.1.2rc12.2.02.2.0rc12.2.12.2.1rc12.3.02.3.0rc12.3.12.3.1rc12.3.22.3.2rc12.4.02.4.0rc12.4.12.4.1rc12.4.22.4.2rc12.4.32.4.3rc12.4.42.4.4rc12.4.52.4.5rc13.0.0rc1
3.0.0

History

History
RecordedChangedSources
first indexedCVE 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

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