Apache Airflow has a Deserialization of Untrusted Data vulnerability
High8.8CVE-2026-42359 · Published Jun 1, 2026 · updated Jul 9, 2026
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.
Affected versions
| Package | Affected | Fixed in |
|---|---|---|
| apache-airflow PyPI | >= 3.2.0, < 3.2.2 | 3.2.2 |
Details and references
- CVSS 3.1
- CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Severity from
- GitHub (reviewed advisory)
- Weakness
- CWE-502
- Also known as
- BIT-airflow-2026-42359, CVE-2026-42359, PYSEC-2026-185
More Apache Airflow advisories
All Apache Airflow| Date | Advisory | Severity | Fixed in |
|---|---|---|---|
| Jun 1 | Apache Airflow has no certificate validation on SMTP STARTTLS connections Medium5.9Jun 1 | Medium5.9 | 3.2.2 |
| Jun 1 | Apache Airflow has an Authorization Bypass Through User-Controlled KeyMedium4.3Jun 1 | Medium4.3 | 3.2.2 |
| Jun 1 | Apache Airflow: Auth manager doesn't invalidate JWT tokens after users click logoutMedium6.5Jun 1 | Medium6.5 | 3.2.2 |
| Jun 1 | Apache Airflow Vulnerable to Deserialization of Untrusted DataHigh7.3Jun 1 | High7.3 | 3.2.2 |
| Jun 1 | Apache Airflow Vulnerable to Exposure of Sensitive Information to an Unauthorized ActorMedium6.5Jun 1 | Medium6.5 | 3.2.2 |
| Jun 1 | Apache Airflow vulnerable to Improper Neutralization of Special Elements Used in a Template EngineCritical9.1Jun 1 | Critical9.1 | 3.2.2 |