Vulnerability 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.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Apache | Airflow | >= 3.2.0, < 3.2.2 |
Related Weaknesses (CWE)
References
- https://github.com/apache/airflow/pull/65915Issue TrackingPatch
- https://lists.apache.org/thread/g8dqykpf1p90tysq8tln4qtkqwb1038sMailing ListVendor Advisory
- https://www.cve.org/CVERecord?id=CVE-2026-33858Third Party Advisory
FAQ
What is CVE-2026-42359?
CVE-2026-42359 is a vulnerability with a CVSS score of 8.8 (HIGH). 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...
How severe is CVE-2026-42359?
CVE-2026-42359 has been rated HIGH with a CVSS base score of 8.8/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-42359?
Check the references section above for vendor advisories and patch information. Affected products include: Apache Airflow.