apache-airflow-providers-smtp: No certificate validation on SMTP STARTTLS connections in SMTP provider

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.9 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS

• CVE-2026-41016: 0.27% estimated exploitation activity in the next 30 days; percentile 18.99 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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.

Published by the source

30 Apr 2026, 12:33 UTC

Last modified by the source

10 Sep 2026, 03:51 UTC

Source last checked

26 Oct 2026, 13:41 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-x8mh-94wc-33gv

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-x8mh-94wc-33gv

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# Patch Next advisory brief: CVE-2026-41016

Advisory: apache-airflow-providers-smtp: No certificate validation on SMTP STARTTLS connections in SMTP provider
IDs: CVE-2026-41016, GHSA-x8mh-94wc-33gv
Record: https://patchnext.com/advisories/cve-2026-41016 (revision 2, source checked 26 Oct 2026, 13:41 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: apache-airflow-providers-smtp 3.0.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI apache-airflow-providers-smtp: affected >= 2.0.0, < 3.0.0; fixed in 3.0.0

## Suggested inspection (read-only)
- `python -m pip show apache-airflow-providers-smtp`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on apache-airflow-providers-smtp.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-x8mh-94wc-33gv (OSV record GHSA-x8mh-94wc-33gv lists affected ranges: PyPI apache-airflow-providers-smtp >=2.0.0 <3.0.0 (fixed))
- Verified: https://github.com/advisories/GHSA-x8mh-94wc-33gv (GitHub-reviewed advisory GHSA-x8mh-94wc-33gv lists affected ranges: PyPI apache-airflow-providers-smtp >=2.0.0 <3.0.0)

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