CVE-2026-42359: Apache Airflow: Authenticated RCE via XCom PATCH endpoint — XComUpdateBody missing FORBIDDEN_XCOM_KEYS validator
This Apache advisory covers CVE-2026-42359 in Apache Airflow.
- CVE-2026-42359
Key facts
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H· base score 8.8, scored by CISA-ADPAttack vector: network. Attack complexity: low. Privileges required: low. User interaction: none. Scope: unchanged. Confidentiality impact: high. Integrity impact: high. Availability impact: high.- Weakness
- CWE-502: Deserialization of Untrusted Data
- CISA SSVC
- Exploitation: none observed. Automatable: no. Technical impact: total. CISA, .
- CISA KEV
- Not listed (catalogue checked )
- Affected
- Apache Airflow 3.2.0 before 3.2.2
- Fixed in
- 3.2.2
- Source published
- Source revised
- Listed by VulniPulse
Compiled by VulniPulse from the linked sources. How records are collected and checked.
Affected products & platforms
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.
Text from the source record.
- Apache Airflow 3.2.0 before 3.2.2
Official advisory · medium-confidence parse· fetched ·verify at source
How to fix CVE-2026-42359
Upgrade to a fixed release named by Apache:
- 3.2.2
Vendor guidance
- 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`.
- 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.
Support dates for the fixed release lines
- Apache Airflow 3.2: support ended
More Apache Software Foundation advisories
CVE-2026-40913Nov 9, 2026Apache Airflow's public Import Errors API returns the raw parse-failure stack trace to anyCVE-2026-50204Nov 9, 2026Apache Airflow's audit log stored Connection and Variable secret values in cleartextCVE-2026-68982Nov 9, 2026Apache Airflow's CeleryExecutor ran callback workloadsCVE-2026-76185Nov 9, 2026Apache Airflow's Task SDK secret cache built its keys from the team name and secret idCVE-2026-86829Nov 9, 2026Apache Airflow's scheduler fully deserializes XCom values written by task codeCVE-2026-82337Nov 9, 2026Apache Airflow rebuilt deadline alert fields through generic deserialization
Apache Software Foundation advisories, June 2026All Apache Software Foundation advisories
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