CVE-2026-49267 is a medium-severity (CVSS 5.9) CWE-295 vulnerability in apache-airflow. A fix is available for apache-airflow — see the affected versions and patch details below.
Apache Airflow: No certificate validation on SMTP STARTTLS connections
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-49267.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-49267 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 386,684 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
apache-airflowReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Apache Airflow's EmailOperator and the underlying airflow.utils.email helpers established SMTP STARTTLS connections without verifying the remote certificate when the deployment used [email] smtp_starttls=True without [email] smtp_ssl. An attacker positioned between the worker and the configured SMTP server (network MITM — typical hostile-network attack-surface for environments where the SMTP relay sits outside the worker's trust boundary) could present a self-signed certificate, have the worker complete the STARTTLS handshake silently, and capture the SMTP AUTH credentials and message contents the worker forwarded.
This CVE covers the core apache-airflow side of the same root cause already covered for the SMTP provider by CVE-2026-41016 (published 2026-04-27, covering apache-airflow-providers-smtp). Users who already applied the SMTP-provider fix from CVE-2026-41016 should additionally upgrade apache-airflow to 3.2.2 or later to cover the core-side path through airflow.utils.email. Affects deployments configured with smtp_starttls=True and smtp_ssl=False where the SMTP relay is reachable across a less-trusted network segment than the worker.
Users are advised to upgrade to apache-airflow 3.2.2 or later.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | apache-airflow | ≥ 2.0.0&&< 3.2.2 | 3.2.2pip install --upgrade 'apache-airflow==3.2.2' |
Affected Products
airflowapacheDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for apache-airflow, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update apache-airflow to 3.2.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-49267 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Frequently Asked Questions
Is CVE-2026-49267 in your dependencies?
Find it across PyPI, including transitive dependencies.