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CVE-2026-42359

Full vulnerability record from the local CVENow database.

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.

Severity
HIGH
CVSS score
8.8 (v3.1)
Vulnerability status
Analyzed
Source identifier
Published
2026-06-01 09:16:18.907000
Last modified
2026-11-03 07:20:20.853000
View original CVE JSON
{
  "id": "CVE-2026-42359",
  "sourceIdentifier": "[email protected]",
  "published": "2026-06-01T09:16:18.907",
  "lastModified": "2026-11-03T07:20:20.853",
  "vulnStatus": "Analyzed",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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."
    },
    {
      "lang": "es",
      "value": "Un error en el endpoint PATCH de XCom de Apache Airflow 'PATCH /api/v2/xcomEntries/{key}' permitió a un usuario autenticado de UI/API con permiso de escritura de XCom en un Dag establecer entradas de XCom bajo nombres de clave reservados (por ejemplo, 'return_value') que el endpoint POST correspondiente ya validaba contra 'FORBIDDEN_XCOM_KEYS'. El endpoint también aceptaba formas de carga útil serializadas que el deserializador del disparador trata como código; combinado, esto permitió RCE en el disparador cuando la tarea afectada se aplazó a continuación. Afecta a implementaciones donde usuarios no confiables tienen permiso de escritura de XCom en Dags que se aplazan al disparador. Esto es un bypass de la corrección de CVE-2026-33858: PR #64148 añadió el validador 'FORBIDDEN_XCOM_KEYS' solo en la ruta POST/set; la ruta PATCH no estaba cubierta. Los usuarios que ya actualizaron para CVE-2026-33858 deberían actualizar adicionalmente a 'apache-airflow' 3.2.2 o posterior para cubrir el bypass de la ruta PATCH."
    }
  ],
  "affected": [
    {
      "source": "[email protected]",
      "affectedData": [
        {
          "vendor": "Apache Software Foundation",
          "product": "Apache Airflow",
          "defaultStatus": "unaffected",
          "collectionURL": "https://pypi.python.org",
          "packageName": "apache-airflow-core",
          "packageURL": "pkg:pypi/apache-airflow-core",
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          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "baseScore": 8.8,
          "baseSeverity": "HIGH",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "privilegesRequired": "LOW",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "HIGH",
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          "id": "CVE-2026-42359",
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  "references": [
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      "url": "https://github.com/apache/airflow/pull/65915",
      "source": "[email protected]",
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}