How severe is CVE-2021-38540?

CVE-2021-38540 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-38540 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 81% (100th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-38540?

CVE-2021-38540 affects Apache Airflow. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-38540?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2021-38540 published?

CVE-2021-38540 was published on 2021-09-09 and last updated on 2026-06-17.

CVE-2021-38540

CVE-2021-38540 is a critical-severity vulnerability in Apache Airflow with a CVSS 3.x base score of 9.8. Its EPSS exploit-prediction score of 81% places it in the 100th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-306.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 81% (100th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-306
Affected product: Apache Airflow
Published: 2021-09-09
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2021-38540?: 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.
How severe is CVE-2021-38540?: CVE-2021-38540 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-38540 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 81% (100th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-38540?: CVE-2021-38540 affects Apache Airflow. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-38540?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-38540 published?: CVE-2021-38540 was published on 2021-09-09 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:apache:airflow:*:*:*:*:*:*:*:*

More vulnerabilities in Apache Airflow

CVE-2026-33264 — Critical (CVSS 9.8): A bug in `BaseSerialization.deserialize()` allowed unrestricted `import_string()` of attacker-controlled class paths…
CVE-2023-25754 — Critical (CVSS 9.8): Privilege Context Switching Error vulnerability in Apache Software Foundation Apache Airflow.This issue affects Apache…
CVE-2023-22884 — Critical (CVSS 9.8): Improper Neutralization of Special Elements used in a Command ('Command Injection') vulnerability in Apache Software…
CVE-2022-40189 — Critical (CVSS 9.8): Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') vulnerability in Apache…
CVE-2022-38649 — Critical (CVSS 9.8): Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') vulnerability in Apache…
CVE-2022-38054 — Critical (CVSS 9.8): In Apache Airflow versions 2.2.4 through 2.3.3, the `database` webserver session backend was susceptible to session…

All CVEs affecting Apache Airflow →

Other CWE-306 (Missing Authentication for Critical Function) vulnerabilities

CVE-2026-20357 — Critical (CVSS 10.0): As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco Crosswork engineering team…
CVE-2026-58115 — Critical (CVSS 10.0): A vulnerability has been identified in SIMATIC IoT2050 Advanced (6ES7647-0BA00-1YA2) (All versions < V4.3.4.1 running…
CVE-2026-63508 — Critical (CVSS 10.0): Missing authentication for critical function in Microsoft Planetary Computer Pro allows an unauthorized attacker to…
CVE-2026-56163 — Critical (CVSS 10.0): Missing authentication for critical function in Microsoft Azure Kubernetes Service allows an unauthorized attacker to…
CVE-2026-64812 — Critical (CVSS 10.0): In JetBrains IntelliJ IDEA before 2026.2 unauthorized input injection was possible in a Remote Development session
CVE-2026-60644 — Critical (CVSS 10.0): Vulnerability in the Oracle WebCenter Content product of Oracle Fusion Middleware (component: Web Content Management).…

Browse all CWE-306 (Missing Authentication for Critical Function) vulnerabilities →