Apache Airflow skips reserved-key check allowing task XComs to instantiate airflow classes (CVE-2026-111421)
Original title: CVE-2026-111421: Apache Airflow: Execution API: set_xcom skips the reserved-key check, so task-written XComs instantiate airflow.* classes on the API server
A task author can write an XCom that causes the Execution API to deserialize and instantiate airflow.* classes in versions before 3.4.0.
Apache Airflow's Task Execution API stored XCom values written by a task without applying the reserved-key check used elsewhere. This allowed a Dag author to submit an XCom that, when viewed through the API with deserialization enabled, caused the API server to instantiate classes from the airflow namespace using arguments from the XCom. The vulnerability affects Apache Airflow 3.0.0 before 3.4.0. Users are advised to upgrade.
- Reserved-key check skipped in set_xcom for task-written XComs
- Deserialization of user-controlled XComs on API server
- Affects 3.0.0 before 3.4.0
Impact: deserialization of task-written XComs allowing arbitrary code execution
- 1.Upgrade to Apache Airflow 3.4.0 or later
Vulnerabilities mentioned
All| CVE | Vulnerability | CVSS | EPSS | Signals | Published |
|---|---|---|---|---|---|
| CVE-2026-111421 | Deserialization RCE in Apache Airflow Execution API | 8.8 | — |
From the original article
Posted by Rahul Vats on Nov 08 Severity: moderate Affected versions: - Apache Airflow 3. 0. 0 before 3.
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