CVE-2026-42359 Apache Airflow: Authenticated RCE via XCom PATCH endpoint — XComUpdateBody missing FORBIDDEN_XCOM_KEYS validator
Authenticated users with XCom write permissions can achieve remote code execution on the triggerer by bypassing input validation on the PATCH endpoint.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-42359?
CVE-2026-42359 is a high-severity unsafe deserialization vulnerability in Apache Airflow, published on 1 Jun 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
A bug in Apache Airflow's XCom PATCH endpoint `PATCH /api/v2/xcomEntries/{key}` allowed an authenticated UI/API user with XCom write permission on a Dag to set XCom entries under reserved key names (e.g. `return_value`) that the matching POST endpoint already validated against `FORBIDDEN_XCOM_KEYS`. The endpoint also accepted serialized payload shapes the triggerer's deserializer treats as code; combined, this allowed RCE on the triggerer when the affected task next deferred. Affects deployments where untrusted users have XCom write permission on Dags that defer to the triggerer. This is a fix-bypass of CVE-2026-33858: PR #64148 added the `FORBIDDEN_XCOM_KEYS` validator only on the POST/set path; the PATCH path was not covered. Users who already upgraded for CVE-2026-33858 should additionally upgrade to `apache-airflow` 3.2.2 or later to cover the PATCH-path bypass.
Weakness: CWE-502
Which versions are affected by CVE-2026-42359?
4 open source packages ship an affected version, including apache-airflow and airflow. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
apache-airflow PyPI | From 3.2.0 | 3.2.2 |
apache-airflow PyPI | From 3.2.0 | 3.2.2 |
apache-airflow PyPI | From 3.2.0 | 3.2.2 |
airflow Bitnami | From 3.2.0 | 3.2.2 |
Products include Apache Airflow.
How do I fix CVE-2026-42359?
Upgrade apache-airflow to 3.2.2 or later.
Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.
Is CVE-2026-42359 being exploited?
There is no known exploitation of CVE-2026-42359 in the wild and no public exploit code.
Other vulnerabilities in Apache Airflow
- CVE-2020-13927 Apache Airflow's Experimental API Authentication Bypass
- CVE-2020-11978 Apache Airflow Command Injection
- CVE-2026-33264 Apache Airflow: DAG author RCE on webserver via unrestricted import_string() in BaseSerialization.deserialize()
- CVE-2023-25754 Apache Airflow: Privilege escalation using airflow logs
- CVE-2023-22884 Apache Airflow, Apache Airflow MySQL Provider: Arbitrary file read via MySQL provider in Apache Airflow
Sources
Also known as BIT-airflow-2026-42359, CLEANSTART-2026-NE51066, ECHO-8570-1636-eec1, GHSA-wr76-29cr-67w8, MINI-2p25-gwpq-2h5m, PYSEC-2026-185.