CVE-2021-35936: Apache Airflow Remote Logging Server Vulnerability
Summary
CVE-2021-35936: If remote logging is not used, the worker (in the case of CeleryExecutor) or the scheduler (in the case of LocalExecutor) runs a Flask logging server and is listening on a specific port and also binds on 0.0.0.0 by defau... Affects apache-airflow versions < 2.1.2. Fixed in 2.1.2. How to fix ↓
Also tracked for
- airflow · Bitnami
The same CVE-2021-35936 is tracked separately for each ecosystem and vendor. Its fix information is the same; the package and affected versions differ.
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Background
Apache Airflow is an open-source platform used for programmatically authoring, scheduling, and monitoring workflows. It provides a rich set of tools and features for managing complex data pipelines. One of its components, the worker (in the case of CeleryExecutor) or the scheduler (in the case of LocalExecutor), runs a Flask logging server to handle logging when remote logging is not enabled. By default, this server listens on a specific port and binds to 0.0.0.0. However, prior to version 2.1.2, the logging server did not have authentication, allowing unauthorized access to log files of DAG (Directed Acyclic Graph) jobs.
Vulnerability Detail
The vulnerability (CVE-2021-35936) in Apache Airflow allows an attacker to read log files of DAG jobs by exploiting the lack of authentication in the Flask logging server. This can lead to unauthorized access to sensitive information contained in the logs, potentially exposing sensitive data or compromising the integrity of the system. The vulnerability affects Apache Airflow versions prior to 2.1.2.
How To Fix
Latest published version: 3.3.2 as of 22 Oct 2026
pip install --upgrade "apache-airflow==3.3.2"Upgrading to it may include breaking changes; the version below is the minimum fixed release for this vulnerability.
If you need the minimum change
2.1.2
This is the first release that contains the fix.
pip install --upgrade "apache-airflow==2.1.2"Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
If upgrading to the latest version is not immediately feasible, a temporary workaround is to enable remote logging in Apache Airflow. By configuring remote logging, the Flask logging server is not used, eliminating the vulnerability. This can be achieved by modifying the Airflow configuration file to specify a remote logging endpoint and credentials.
Conclusion
The Apache Airflow Remote Logging Server vulnerability (CVE-2021-35936) allows unauthorized access to log files of DAG jobs. To mitigate this vulnerability, it is crucial to upgrade to Apache Airflow version 2.1.2 or later. Alternatively, enabling remote logging can serve as a temporary workaround. For further assistance in vulnerability remediation, please contact DevNack.com.
See every vulnerability recorded for apache-airflow →
FAQ
Apache Airflow is an open-source platform for programmatically authoring, scheduling, and monitoring workflows. It provides a rich set of tools and features for managing complex data pipelines.
The vulnerability allows unauthorized access to log files of DAG jobs in Apache Airflow. This can potentially expose sensitive information and compromise the integrity of the system.
The vulnerability affects Apache Airflow versions prior to 2.1.2.
To fix this vulnerability, it is recommended to upgrade Apache Airflow to version 2.1.2 or later.
Yes, a temporary workaround is to enable remote logging in Apache Airflow by configuring the Airflow configuration file.
References
Related vulnerabilities
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