CVE-2021-38540 is a critical-severity (CVSS 9.8) Improper Privilege Management vulnerability in apache-airflow. 2 public exploit or proof-of-concept references are indexed, so weaponization risk is real. A fix is available for apache-airflow — see the affected versions and patch details below.
Missing Authentication for Critical Function in Apache Airflow
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
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
The variable import endpoint was not protected by authentication in Airflow >=2.0.0, <2.1.3. This allowed unauthenticated users to hit that endpoint to add/modify Airflow variables used in DAGs, potentially resulting in a denial of service, information disclosure or remote code execution. This issue affects Apache Airflow >=2.0.0, <2.1.3.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | apache-airflow | ≥ 2.0.0&&< 2.1.3 | 2.1.3pip install --upgrade 'apache-airflow==2.1.3' |
Affected Products
airflowapacheResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & 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 2.1.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-38540 is resolved across your whole dependency graph.
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.
How to detect CVE-2021-38540
A community-maintained Nuclei template exists for this CVE. You can scan for it directly:
nuclei -id cve-2021-38540 -u https://target- Template
- Apache Airflow - Unauthenticated Variable Import
- Severity
- critical
- Impact
- An attacker can exploit this vulnerability to import malicious variables, potentially gaining unauthorized access to sensitive data.
- Remediation
- Upgrade to Apache Airflow 2.1.3 or higher.
Template by ProjectDiscovery nuclei-templates (pdteam), MIT licensed. View the full template. Scan only systems you are authorised to test.
Frequently Asked Questions
Is CVE-2021-38540 in your dependencies?
Find it across PyPI, including transitive dependencies.