How severe is CVE-2021-38540?

CVE-2021-38540 has a CVSS score of 9.8/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by CVE-2021-38540?

CVE-2021-38540 affects the following packages: apache-airflow (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2021-38540?

Update apache-airflow to version 2.1.3 or later. Run your dependency manager's update command and verify no transitive dependencies pin the vulnerable version. Use O3 Security's SCA scanner to confirm the fix is applied across your entire dependency tree.

Is CVE-2021-38540 actively exploited in the wild?

Yes. There are 2 known exploit references for CVE-2021-38540, including 1 in-the-wild exploitation observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2021-38540?

CVE-2021-38540 has an EPSS (Exploit Prediction Scoring System) score of 91.8%, placing it in the 100th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. A score above 50% indicates significantly elevated exploitation risk — immediate patching is strongly recommended.

What type of vulnerability is CVE-2021-38540?

CVE-2021-38540 is classified as Improper Privilege Management (CWE-269), Missing Authentication (CWE-306). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

Is there exploit tooling available for CVE-2021-38540?

A Nuclei detection template exists for CVE-2021-38540, meaning automated scanners can fingerprint it. Public exploit tooling significantly increases real-world risk — prioritize patching and ensure detection coverage. Exploit tooling should only ever be used in isolated, authorized testing environments.

When was CVE-2021-38540 published, and has it been updated?

CVE-2021-38540 was published on September 9, 2021 and was last updated on March 14, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍 PyPI

CVE-2021-38540

CRITICAL

Missing Authentication for Critical Function in Apache Airflow

Also known asBIT-airflow-2021-38540GHSA-h88f-r7cw-8fv3PYSEC-2021-326

Published

Sep 9, 2021

Updated

Mar 14, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

2 known

EPSS Exploitation Probability

via FIRST.org ↗

91.8%probability of exploitation in next 30 days

Very High Risk100th percentile0.00%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

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

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

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`apache-airflow`	≥ 2.0.0&&< 2.1.3	2.1.3

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

The variable import endpoint was not protected by authentication in Airf…

github.comGithubJun 2022

Frequently Asked Questions

O3 Security · Impact-Aware SCA

Is CVE-2021-38540 in your stack?

O3 detects CVE-2021-38540 across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my stack How O3 SCA works