Apache Airflow: Authenticated RCE via XCom PATCH endpoint — XComUpdateBody missing FORBIDDEN_XCOM_KEYS validator

{
  "id": "3360f9c1ac5e0e83cf370d4a98aece7d77d46de02f27d992e3c2b3ab39ff62ea",
  "url": "https://osv.dev/vulnerability/CVE-2026-42359",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Apache Airflow: Authenticated RCE via XCom PATCH endpoint — XComUpdateBody missing FORBIDDEN_XCOM_KEYS validator",
    "summary": "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.",
    "evidence": "osv:CVE-2026-42359",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-42359",
      "aliases": [
        "BIT-airflow-2026-42359",
        "CVE-2026-42359",
        "GHSA-wr76-29cr-67w8",
        "PYSEC-2026-185"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/apache/airflow",
              "type": "GIT",
              "events": [
                {
                  "introduced": "37069948c093e4b6720ec4821ff0ed7d6c069935"
                },
                {
                  "fixed": "21cbbf663b140f4a84cf123acb90328a6a4d30f5"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "3.2.0"
                      },
                      {
                        "fixed": "3.2.2"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "cpe": "cpe:2.3:a:apache:airflow:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "3.2.0"
                      },
                      {
                        "fixed": "3.2.2"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "task-sdk/1.2.2rc3",
            "task-sdk/1.2.2",
            "3.2.2rc3",
            "3.2.2",
            "task-sdk/1.2.2rc2",
            "3.2.2rc2",
            "task-sdk/1.2.2rc1",
            "3.2.2rc1",
            "python-client/3.2.1rc1",
            "python-client/3.2.1",
            "task-sdk/1.2.1rc3",
            "task-sdk/1.2.1",
            "3.2.1rc3",
            "3.2.1",
            "task-sdk/1.2.1rc2",
            "3.2.1rc2",
            "task-sdk/1.2.1rc1",
            "3.2.1rc1",
            "python-client/3.2.0rc1",
            "python-client/3.2.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-42359.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:31.212460218Z",
      "provider": "osv",
      "references": [
        "https://pypi.python.org",
        "https://www.cve.org/CVERecord?id=CVE-2026-33858",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42359.json",
        "https://lists.apache.org/thread/g8dqykpf1p90tysq8tln4qtkqwb1038s",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-42359",
        "https://github.com/apache/airflow/pull/65915"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-502"
        ],
        "cna_assigner": "apache",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42359.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-42359",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 498113,
  "published_at": "2026-06-01T07:49:17.429+00:00"
}