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MEDIUM severity

CVE-2021-26559 — apache-airflow

MEDIUMFix: apache/airflow@3909232

CVE-2021-26559 is a medium-severity (CVSS 6.5) CWE-284 vulnerability in apache-airflow. A fix is available for apache-airflow — see the affected versions and patch details below.

Improper Access Control in Apache Airflow

Also known asBIT-airflow-2021-26559GHSA-ffw3-6mp6-jmvjPYSEC-2021-2
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Oct 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
2.8%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs86th percentile — riskier than 86% of all scored CVEsHighest risk
0.00%1.16%2.32%3.48%0.6%2.8%Apr 26Aug 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2021-26559 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected
🐍apache-airflow

Real-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

Improper Access Control on Configurations Endpoint for the Stable API of Apache Airflow allows users with Viewer or User role to get Airflow Configurations including sensitive information even when [webserver] expose_config is set to False in airflow.cfg. This allowed a privilege escalation attack. This issue affects Apache Airflow 2.0.0.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐍PyPIapache-airflow≥ 2.0.0&&< 2.0.1rc12.0.1rc1pip install --upgrade 'apache-airflow==2.0.1rc1'

Affected Products

1 product · 1 configurations
Application
airflowapache
1 version
2.0.0

Detection & mitigation playbook

Open-source dependency

  1. Detect

    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.

  2. Fix

    Update apache-airflow to 2.0.1rc1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-26559 is resolved across your whole dependency graph.

  3. Workarounds

    Close the privilege gap rather than the entry point: audit which accounts, roles and service identities can reach the affected operation, drop the component to the least privilege it actually needs, and review file and directory permissions created by earlier installs — a default left in place is what makes this reachable.

Frequently Asked Questions

Improper Access Control on Configurations Endpoint for the Stable API of Apache Airflow allows users with Viewer or User role to get Airflow Configurations including sensitive information even when `[webserver] expose_config` is set to `False` in `airflow.cfg`. This allowed a privilege escalation attack. This issue affects Apache Airflow 2.0.0.
O3 Security · Impact-Aware SCA

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CVE-2021-26559: apache-airflow PrivEsc — Fixed in 2.0.1rc1