{"id":"CVE-2026-42359","aliases":["BIT-airflow-2026-42359","GHSA-wr76-29cr-67w8","PYSEC-2026-185"],"url":"https://o3.security/vulnerability/CVE-2026-42359","summary":"Apache Airflow: Authenticated RCE via XCom PATCH endpoint — XComUpdateBody missing FORBIDDEN_XCOM_KEYS validator","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.","published":"2026-06-01T07:49:17.429Z","modified":"2026-08-12T03:51:41.811686029Z","cvss":{"score":8.8,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"},"epss":{"score":0.00571,"percentile":0.4463,"asOf":"2026-08-24"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"apache-airflow","fixedVersion":"3.2.2"}],"fix":{"url":"https://github.com/apache/airflow/pull/65915","label":"apache/airflow#65915"},"references":[{"type":"WEB","url":"https://pypi.python.org"},{"type":"WEB","url":"https://www.cve.org/CVERecord?id=CVE-2026-33858"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42359.json"},{"type":"ADVISORY","url":"https://lists.apache.org/thread/g8dqykpf1p90tysq8tln4qtkqwb1038s"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-42359"},{"type":"FIX","url":"https://github.com/apache/airflow/pull/65915"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:41.811686029Z"}}