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Medium

Apache Airflow has no certificate validation on SMTP STARTTLS connections

  • Disclosed: 01.06.2026
  • Updated: 11.10.2026 14:18

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 software

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PlatformPackageVulnerable versionsFixed in
Python (PyPI) apache-airflow >= 2.0.0, < 3.2.2 3.2.2

References

CVSS score 5.9/10
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Weakness (CWE)
CWE-295
Platform
Python (PyPI)
Package
apache-airflow
Disclosed
01.06.2026
Updated
11.10.2026 14:18

Sources and licenses

OSV / GitHub Advisory Database - GHSA-799x-qp47-8qwq - CC BY 4.0

OSV / GitHub Advisory Database - PYSEC-2026-2346 - PyPA Advisory Database; CC BY 4.0

Vulnerability history: apache-airflow

All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.

All (158) in the archive
Total entries
158
First → latest
08.2018 09.2026
Without a fix
4
Exploited in attacks
2

Severity breakdown

  • Critical 16
  • High 49
  • Medium 86
  • Low 7

Disclosures per year

Severity:
  1. Apache Airflow: the Core API logout endpoint revokes only a session token presented as the _token cookie. When a client logs out presenting its credential as an Authorization bearer header instead, th
    Critical · 9.1 CVE-2026-86473 >= 3.0.0, < 3.3.2 3.3.2
  2. Apache Airflow's Backfill API authorized a request against a Dag id supplied by the caller whenever the `backfill_id` path segment failed to parse. The authorization dependency parsed it with `int()`
    High · 7.5 CVE-2026-68968 < 3.3.1 3.3.1
  3. Apache Airflow's Task SDK rebuilt a `Callback` object from serialized data by re-running its constructor, which imports the module named by the stored callback path. Because `SyncCallback` is itself a
    High · 8.8 CVE-2026-67587 >= 3.3.0, < 3.3.1 3.3.1
  4. Apache Airflow 3.3.0 moved human-in-the-loop tasks from the triggerer to a new `awaiting_input` task state swept by the scheduler. That sweep deserializes the task instance's `next_kwargs` without an
    High · 7.3 CVE-2026-67260 >= 3.3.0, < 3.3.1 3.3.1
  5. Apache Airflow's serialization layer reconstructed exception nodes by calling `import_string()` on a class name taken from the serialized blob and instantiating it with arguments from the same blob, w
    High · 8.8 CVE-2026-58076 >= 3.3.0, < 3.3.1 3.3.1
  6. A bug in `BaseSerialization.deserialize()` allowed unrestricted `import_string()` of attacker-controlled class paths when the Scheduler / API Server loaded a serialized DAG: a DAG author could embed a
    Critical · 9.8 CVE-2026-33264 < 3.3.0 3.3.0
  7. Apache Airflow has no certificate validation on SMTP STARTTLS connections this entry
    Medium · 5.9 CVE-2026-49267 >= 2.0.0, < 3.2.2 3.2.2
  8. A bug in Apache Airflow's XCom PATCH endpoint `PATCH /api/v2/xcomEntries/{key}` allowed an authenticated UI/API user with XCom write permission on a Dag to set XCom entries under reserved key names (e
    High · 8.8 CVE-2026-42359 >= 3.2.0, < 3.2.2 3.2.2
  9. A bug in Apache Airflow's bulk Task Instances API (`PATCH/DELETE /api/v2/dags/{dag_id}/dagRuns/{dag_run_id}/taskInstances`) evaluated authorization against the `dag_id` resolved from the URL path whil
    High · 7.5 CVE-2026-41084 >= 3.2.0, < 3.2.2 3.2.2
  10. Apache Airflow's official documentation at `core-concepts/dag-run.html` ("Passing Parameters when triggering Dags") showed a verbatim `BashOperator(bash_command="echo value: {{ dag_run.conf['conf1'] }
    Critical · 9.1 CVE-2026-42252 >= 3.0.0, < 3.2.2 3.2.2
  11. Apache Airflow: Authenticated users can bypass the `is_safe_url` check
    High · 7.2 CVE-2026-40961 < 3.2.2 3.2.2
  12. Apache Airflow Vulnerable to Deserialization of Untrusted Data
    High · 7.3 CVE-2026-45360 >= 3.2.0, < 3.2.2 3.2.2
  13. Apache Airflow allows code execution through crafted XCom payloads
    High · 7.2 CVE-2026-25917 < 3.2.0 3.2.0
  14. Apache Airflow: JWT token appearing in logs
    High · 7.5 CVE-2026-31987 >= 3.0.0, < 3.2.0 3.2.0
  15. Apache Airflow: RCE by race condition in example_xcom dag
    High · 8.1 CVE-2025-54550 < 3.2.0 3.2.0
  16. Dag Authors, who normally should not be able to execute code in the webserver context could craft XCom payload causing the webserver to execute arbitrary code. Since Dag Authors are already highly tru
    High · 8.8 CVE-2026-33858 >= 3.1.8, < 3.2.0 3.2.0
  17. Apache Airflow: JWT token still valid after logout
    Critical · 9.1 CVE-2025-57735 >= 3.0.0, < 3.2.0 3.2.0
  18. Apache Airflow versions 3.1.0 through 3.1.7 missing authorization vulnerability in the Execution API's Human-in-the-Loop (HITL) endpoints that allows any authenticated task instance to read, approve,
    High · 8.1 CVE-2026-30911 >= 3.1.0, < 3.1.8 3.1.8
  19. Apache Airflow versions 3.1.0 through 3.1.7 session token (_token) in cookies is set to path=/ regardless of the configured [webserver] base_url or [api] base_url.
    High · 7.5 CVE-2026-28779 >= 3.0.0, < 3.1.8 3.1.8
  20. Apache Airflow vulnerable to Code Injection in the web-server context via LogTemplate table
    High · 8.4 CVE-2024-56373 < 2.11.1 2.11.1
  21. Apache Airflow proxy credentials for various providers might leak in task logs
    High · 7.5 CVE-2025-68675 >= 3.0.0b1, < 3.1.6, < 2.11.1 3.1.6, 2.11.1
  22. Apache Airflow secrets in rendered templates could contain parts of sensitive values when truncated
    High · 7.5 CVE-2025-68438 >= 3.1.0, < 3.1.6 3.1.6
  23. Apache Airflow Providers Edge3 exposes internal API allowing RCE in web server context
    Critical · 9.8 CVE-2025-67895 < 2.0.0 2.0.0
  24. Apache Airflow: Sensitive configuration values are not masked in the logs by default
    High · 7.5 CVE-2024-45784 < 2.10.3 2.10.3
  25. Apache Airflow vulnerable to Improper Encoding or Escaping of Output
    High · 8.8 CVE-2024-45498 >= 2.10.0, < 2.10.1 2.10.1
  26. Apache Airflow vulnerable to Execution with Unnecessary Privileges
    High · 8.8 CVE-2024-45034 < 2.10.1 2.10.1
  27. Apache Airflow has DAG Author Code Execution possibility in airflow-scheduler
    High · 8.8 CVE-2024-39877 >= 2.4.0, < 2.9.3 2.9.3
  28. Apache Airflow, versions before 2.8.1, have a vulnerability that allows a potential attacker to poison the XCom data by bypassing the protection of "enable_xcom_pickling=False" configuration setting r
    High · 7.5 CVE-2023-50943 < 2.8.1 2.8.1
  29. Apache Airflow, versions before 2.8.1, have a vulnerability that allows an authenticated user to access the source code of a DAG to which they don't have access. This vulnerability is considered low s
    High · 6.5 CVE-2023-50944 < 2.8.1 2.8.1
  30. Apache Airflow, versions before 2.7.3, has a vulnerability that allows an authorized user who has access to read specific DAGs only, to read information about task instances in other DAGs.  This is a
    High · 6.5 CVE-2023-42781 < 2.7.3 2.7.3
  31. Apache Airflow Celery provider Insertion of Sensitive Information into Log File vulnerability
    High · 7.5 CVE-2023-46215 >= 1.10.0, < 2.7.0 2.7.0
  32. Apache Airflow, versions before 2.7.1, is affected by a vulnerability that allows authenticated users who have access to see the task/dag in the UI, to craft a URL, which could lead to unmasking the s
    High · 6.5 CVE-2023-40712 < 2.7.1 2.7.1
  33. Apache Airflow, in versions prior to 2.7.0, contains a security vulnerability that can be exploited by an authenticated user possessing Connection edit privileges. This vulnerability allows the user t
    High · 8.1 CVE-2023-37379 < 2.7.0 2.7.0
  34. The session fixation vulnerability allowed the authenticated user to continue accessing Airflow webserver even after the password of the user has been reset by the admin - up until the expiry of the s
    High · 8.0 CVE-2023-40273 < 2.7.1rc1 2.7.1rc1
  35. apache-airflow-providers-apache-drill Improper Input Validation vulnerability
    High · 7.5 CVE-2023-39553 < 2.4.3 2.4.3
  36. Execution with Unnecessary Privileges, : Exposure of Sensitive Information to an Unauthorized Actor vulnerability in Apache Software Foundation Apache Airflow.The "Run Task" feature enables authentica
    High · 8.8 CVE-2023-39508 < 2.6.0 2.6.0
  37. Apache Airflow, versions before 2.6.3, is affected by a vulnerability that allows an unauthorized actor to gain access to sensitive information in Connection edit view. This vulnerability is considere
    High · 6.5 CVE-2022-46651 < 2.6.3 2.6.3
  38. Apache Airflow, versions before 2.6.3, is affected by a vulnerability that allows unauthorized read access to a DAG through the URL. It is recommended to upgrade to a version that is not affected
    High · 6.5 CVE-2023-35908 < 2.6.3 2.6.3
  39. Apache Airflow, versions before 2.6.3, is affected by a vulnerability that allows an attacker to cause a service disruption by manipulating the run_id parameter. This vulnerability is considered low s
    High · 6.5 CVE-2023-22888 < 2.6.3 2.6.3
  40. Apache Airflow, versions before 2.6.3, has a vulnerability where an authenticated user can use crafted input to make the current request hang. It is recommended to upgrade to a version that is not aff
    High · 6.5 CVE-2023-36543 < 2.6.3 2.6.3
  41. Apache Airflow, versions before 2.6.3, is affected by a vulnerability that allows an attacker to perform unauthorized file access outside the intended directory structure by manipulating the run_id pa
    High · 6.5 CVE-2023-22887 < 2.6.3 2.6.3
  42. In Apache Airflow, some potentially sensitive values were being shown to the user in certain situations.
    High · 6.5 CVE-2023-35005 >= 2.5.0, < 2.6.2 2.6.2
  43. Privilege Context Switching Error vulnerability in Apache Software Foundation Apache Airflow.This issue affects Apache Airflow: before 2.6.0.
    Critical · 9.8 CVE-2023-25754 < 2.6.0 2.6.0
  44. Apache Airflow Drill Provider vulnerable to improper input validation
    High · 7.5 CVE-2023-28707 < 2.3.2 2.3.2
  45. Apache Airflow Sqoop Provider Improper Input Validation vulnerability
    Critical · 9.8 CVE-2023-25693 < 3.1.1 3.1.1
  46. Command Injection in Apache Airflow and Apache Airflow MySQL Provider
    Critical · 9.8 CVE-2023-22884 < 2.5.1 2.5.1
  47. OS Command Injection in Apache Airflow
    Critical · 9.8 CVE-2022-38649 < 2.3.0 2.3.0
  48. OS Command Injection in Apache Airflow
    Critical · 9.8 CVE-2022-40189 < 2.3.0 2.3.0
  49. A vulnerability in UI of Apache Airflow allows an attacker to view unmasked secrets in rendered template values for tasks which were not executed (for example when they were depending on past and prev
    High · 7.5 CVE-2022-27949 < 2.3.1 2.3.1
  50. A vulnerability in Example Dags of Apache Airflow allows an attacker with UI access who can trigger DAGs, to execute arbitrary commands via manually provided run_id parameter. This issue affects Apach
    High · 8.8 CVE-2022-40127 < 2.4.0 2.4.0
  51. In Apache Airflow, prior to version 2.4.1, deactivating a user wouldn't prevent an already authenticated user from being able to continue using the UI or API.
    High · 8.1 CVE-2022-41672 < 2.4.2rc1 2.4.2rc1
  52. In Apache Airflow 2.3.0 through 2.3.4, part of a url was unnecessarily formatted, allowing for possible information extraction.
    High · 7.5 CVE-2022-40604 >= 2.3.0, < 2.4.0b1 2.4.0b1
  53. Apache Airflow Session Fixation vulnerability
    Critical · 9.8 CVE-2022-38054 >= 2.2.4, < 2.3.4rc1 2.3.4rc1
  54. OS Command injection in Apache Airflow
    High · 8.8 CVE-2022-24288 < 2.2.4 2.2.4
  55. Missing Authentication for Critical Function in Apache Airflow
    Critical · 9.8 CVE-2021-38540 >= 2.0.0, < 2.1.3 2.1.3
  56. Improper Access Control in Apache Airflow
    High · 6.5 CVE-2021-26559 >= 2.0.0, < 2.0.1rc1 2.0.1rc1
  57. Incorrect Session Validation in Apache Airflow
    High · 7.7 CVE-2020-17526 < 1.10.14 1.10.14
  58. Authentication bypass in Apache Airflow
    Critical · 9.8 Exploited in attacks CVE-2020-13927 < 1.10.11 1.10.11
  59. Insecure default config of Celery worker in Apache Airflow
    Critical · 9.8 CVE-2020-11982 < 1.10.11 1.10.11
  60. Command injection via Celery broker in Apache Airflow
    Critical · 9.8 CVE-2020-11981 < 1.10.11rc1 1.10.11rc1
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