CVE-2021-29621 Observable Response Discrepancy in Flask-AppBuilder

What is CVE-2021-29621?

CVE-2021-29621 is a medium-severity vulnerability in Apache Airflow, published on 7 Jun 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

Flask-AppBuilder is a development framework, built on top of Flask. User enumeration in database authentication in Flask-AppBuilder <= 3.2.3. Allows for a non authenticated user to enumerate existing accounts by timing the response time from the server when you are logging in. Upgrade to version 3.3.0 or higher to resolve.

Weakness: CWE-203

Which versions are affected by CVE-2021-29621?

4 open source packages ship an affected version, including airflow, Flask-AppBuilder and flask-appbuilder. It affects 2 products.

Products include Apache Airflow, Dpgaspar Flask-Appbuilder.

How do I fix CVE-2021-29621?

Upgrade airflow to 1.10.1 or later.

Is CVE-2021-29621 being exploited?

There is no known exploitation of CVE-2021-29621 in the wild and no public exploit code.

Other vulnerabilities in Apache Airflow

• CVE-2020-13927 Apache Airflow's Experimental API Authentication Bypass Exploited Critical 9.8
• CVE-2020-11978 Apache Airflow Command Injection Exploited High 8.8
• CVE-2026-33264 Apache Airflow: DAG author RCE on webserver via unrestricted import_string() in BaseSerialization.deserialize() Critical 9.8
• CVE-2023-25754 Apache Airflow: Privilege escalation using airflow logs Critical 9.8
• CVE-2023-22884 Apache Airflow, Apache Airflow MySQL Provider: Arbitrary file read via MySQL provider in Apache Airflow Critical 9.8

All Apache Airflow vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BIT-airflow-2021-29621, GHSA-434h-p4gx-jm89, PYSEC-2021-90.