CVE-2026-41016: apache-airflow-providers-smtp No Certificate Validation On SMTP Vulnerability

MODERATE
Advisory Identifier: GHSA-x8mh-94wc-33gv
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CVSS 5.9
CWE-295
Published
Advisory Summary

CVE-2026-41016 is a MODERATE (CVSS 5.9) no certificate validation on smtp vulnerability (CWE-295: Improper Certificate Validation) affecting apache-airflow-providers-smtp libraries in the PyPI ecosystem. The issue involves no certificate validation on smtp starttls connections in smtp provider. Remediation is available by upgrading affected packages to version 3.0.0.

CVE-2026-41016 at a Glance

CVE Identifier CVE-2026-41016
GHSA Identifier GHSA-x8mh-94wc-33gv
Severity MODERATE
CVSS v3.1 Base Score 5.9
CWE Classification CWE-295: Improper Certificate Validation
Affected Product apache-airflow-providers-smtp
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 5.9

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N).

Attack Vector Network (AV:N)
Attack Complexity High (AC:H)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity None (I:N)
Availability None (A:N)

How to Fix CVE-2026-41016

To remediate this vulnerability, upgrade all affected apache-airflow-providers-smtp dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

apache-airflow-providers-smtp fixed: 3.0.0 
pip install apache-airflow-providers-smtp>=3.0.0
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show apache-airflow-providers-smtp

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2026-41016, inspect your installed packages using pip:

pip show apache-airflow-providers-smtp

Analyze the terminal output to locate any version of apache-airflow-providers-smtp in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 3.0.0), your application is affected.

Note: The pip show apache-airflow-providers-smtp command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-295: Improper Certificate Validation, where the product does not validate, or incorrectly validates, a certificate. In apache-airflow-providers-smtp, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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.

CVE-2026-41016 Affected apache-airflow-providers-smtp Versions

1 component(s)
Fixed Versions:
3.0.0
Product / Package Ecosystem Affected Versions Fixed Version
apache-airflow-providers-smtp
pypi/apache-airflow-providers-smtp
PyPI
≥ 2.0.0
< 3.0.0
3.0.0

References

NVD — CVE-2026-41016 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-41016
apache-airflow-providers-smtp Source Repository REPOSITORY
https://github.com/apache/airflow/pull/65346
apache-airflow-providers-smtp Source Repository REPOSITORY
https://github.com/apache/airflow
apache-airflow-providers-smtp Source Repository REPOSITORY
https://github.com/pypa/advisory-database/tree/main/vulns/apache-airflow-providers-smtp/PYSEC-2026-24.yaml
lists.apache.org/thread/gb202qy5r31b... WEB
https://lists.apache.org/thread/gb202qy5r31bgdd3d51d7s5o1jh40kc4

Frequently Asked Questions

What is CVE-2026-41016?
CVE-2026-41016 is a security vulnerability in apache-airflow-providers-smtp involving No certificate validation on SMTP STARTTLS connections in SMTP provider under CWE-295: Improper Certificate Validation.
Which apache-airflow-providers-smtp versions are affected?
Affected versions include releases prior to 3.0.0 across affected packages: apache-airflow-providers-smtp.
What version fixes CVE-2026-41016?
Upgrading to 3.0.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is apache-airflow-providers-smtp affected?
Yes, apache-airflow-providers-smtp is affected in releases prior to 3.0.0. Upgrade your dependency to 3.0.0 or later.
What is the CVSS score of CVE-2026-41016?
CVE-2026-41016 has a CVSS v3.1 base score of 5.9 (MODERATE) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N.
What CWE is associated with CVE-2026-41016?
CVE-2026-41016 is classified under CWE-295: Improper Certificate Validation (The product does not validate, or incorrectly validates, a certificate.).
How can I check PyPI dependencies for CVE-2026-41016?
Run the dependency tree command: 'pip show apache-airflow-providers-smtp'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-x8mh-94wc-33gv",
  "modified" : "2026-05-22T13:04:58Z",
  "published" : "2026-04-30T12:33:11Z",
  "aliases" : [ "CVE-2026-41016" ],
  "summary" : "apache-airflow-providers-smtp: No certificate validation on SMTP STARTTLS connections in SMTP provider",
  "details" : "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.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "apache-airflow-providers-smtp"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.0.0"
      }, {
        "fixed" : "3.0.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-41016"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/apache/airflow/pull/65346"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/apache/airflow"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/apache-airflow-providers-smtp/PYSEC-2026-24.yaml"
  }, {
    "type" : "WEB",
    "url" : "https://lists.apache.org/thread/gb202qy5r31bgdd3d51d7s5o1jh40kc4"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-295" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-22T13:04:58Z",
    "nvd_published_at" : "2026-04-30T10:16:01Z"
  }
}