CVE-2026-42359

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.

CVSS v3 8.8 HIGH

8.8^/10

CVSS v3 : HIGH

Vector :

Exploitability : 2.8 / Impact : 5.9

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required LOW

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/apache/airflow/pull/65915	Issue Tracking Patch
https://lists.apache.org/thread/g8dqykpf1p90tysq8tln4qtkqwb1038s	Mailing List Vendor Advisory
https://www.cve.org/CVERecord?id=CVE-2026-33858	Third Party Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:apache:airflow:*:*:*:*:*:*:*:*

History

No history.

Information

Published : 2026-06-01 09:16

Updated : 2026-07-21 19:10

NVD link : CVE-2026-42359

Mitre link : CVE-2026-42359

CVE.ORG link : CVE-2026-42359

JSON object : View

Products Affected

apache

airflow

CWE

CWE-502

Deserialization of Untrusted Data

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