CVE-2026-33858 Apache Airflow: Unsafe Deserialization via Legacy Serialization Keys (__type/__var) Bypass in XCom API

What is CVE-2026-33858?

CVE-2026-33858 is a high-severity unsafe deserialization vulnerability in Apache Airflow, published on 13 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

Dag Authors, who normally should not be able to execute code in the webserver context could craft XCom payload causing the webserver to execute arbitrary code. Since Dag Authors are already highly trusted, severity of this issue is Low.

Users are recommended to upgrade to Apache Airflow 3.2.0, which resolves this issue.

Weakness: CWE-502

Which versions are affected by CVE-2026-33858?

4 open source packages ship an affected version, including apache-airflow and airflow. It affects 1 product.

Products include Apache Airflow.

How do I fix CVE-2026-33858?

Upgrade apache-airflow to 3.2.0 or later.

Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.

Is CVE-2026-33858 being exploited?

There is no known exploitation of CVE-2026-33858 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-2026-33858, ECHO-a0ac-41bb-a272, GHSA-mc4f-r875-v87w, MINI-97fw-3337-7rq4, PYSEC-2026-20.