{"id":"PYSEC-2026-185","details":"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.","aliases":["BIT-airflow-2026-42359","CVE-2026-42359","GHSA-wr76-29cr-67w8"],"modified":"2026-07-13T16:50:05.952582850Z","published":"2026-06-01T09:16:18.907Z","references":[{"type":"ADVISORY","url":"https://lists.apache.org/thread/g8dqykpf1p90tysq8tln4qtkqwb1038s"},{"type":"ADVISORY","url":"https://www.cve.org/CVERecord?id=CVE-2026-33858"},{"type":"FIX","url":"https://github.com/apache/airflow/pull/65915"},{"type":"ADVISORY","url":"https://github.com/advisories/GHSA-wr76-29cr-67w8"}],"affected":[{"package":{"name":"apache-airflow","ecosystem":"PyPI","purl":"pkg:pypi/apache-airflow"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.2.0"},{"fixed":"3.2.2"}]}],"versions":["3.2.0","3.2.1","3.2.1rc1","3.2.1rc2","3.2.1rc3","3.2.2rc1","3.2.2rc2","3.2.2rc3"],"ecosystem_specific":{},"database_specific":{"source":"https://github.com/pypa/advisory-database/blob/main/vulns/apache-airflow/PYSEC-2026-185.yaml"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}