CVE-2021-35936: No Authentication on Logging Server

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 5.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-08-16 · updated 2026-06-17
Weakness: CWE-200

Description

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 default. This logging server had no authentication and allows reading log files of DAG jobs. This issue affects Apache Airflow < 2.1.2.

Affected products

Apache Airflow: before 2.1.2 — fixed in 2.1.2

How to fix

Upgrade to a fixed version: Apache Airflow 2.1.2. Check the vendor advisory for mitigations.

References

https://lists.apache.org/thread.html/r53d6bd7b0a66f92ddaf1313282f10fec802e71246606dd30c16536df%40%3Cusers.airflow.apache.org%3E
https://lists.apache.org/thread.html/r53d6bd7b0a66f92ddaf1313282f10fec802e71246606dd30c16536df%40%3Cusers.airflow.apache.org%3E

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