# CVE-2026-33858: Apache Airflow insecure deserialization in XCom API

Source: https://junglewise.ai/threats/cve-2026-33858-apache-airflow-insecure-deserialization-in-xcom-api  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-13. Updated: 2026-06-05  
License: CC BY 4.0 with a link back

CVE-2026-33858 · Severity: high · CVSS 8.8 · Published 2026-04-13

Apache Airflow is an open-source platform used to schedule and monitor complex workflows. A vulnerability in the way it handles internal data sharing (XCom) allows users who can author workflows (DAGs) to execute unauthorized code on the central webserver. While workflow authors are typically trusted users, this flaw allows them to escalate their privileges and potentially compromise the entire Airflow environment or access sensitive data.

Technologies: [Apache Airflow](https://junglewise.ai/threats/technologies/airflow), [apache-airflow (PyPI)](https://junglewise.ai/threats/technologies/apache-airflow). Vendors: [Apache](https://junglewise.ai/threats/vendors/apache), [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is CVE-2026-33858 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-33858 being exploited in the wild.

**How severe is CVE-2026-33858?** High severity, with a CVSS score of 8.8, published 13 April 2026.

**Which products and versions are affected?** Apache Airflow >= 3.1.8, < 3.2.0; apache-airflow (PyPI) >= 3.1.8, < 3.2.0, ECOSYSTEM:introduced=3.1.8,fixed=3.2.0.

**Is there a fix for CVE-2026-33858?** Yes. apache-airflow (PyPI): upgrade to 3.2.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-33858 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-33858?** Check whether you run Apache Airflow or apache-airflow (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- apache-airflow (PyPI): upgrade to 3.2.0 or later

  ```sh
  pip install "apache-airflow>=3.2.0"
  ```


## Technical details

A vulnerability exists in Apache Airflow's XCom API due to unsafe deserialization of untrusted data (CWE-502). The root cause is a bypass of legacy serialization key protections (specifically `__type` and `__var`) that occurred during a refactoring of the task-sdk and core dependencies. An attacker with DAG author privileges can craft a malicious XCom payload that, when processed by the webserver, triggers arbitrary code execution. This effectively allows a user with 'Low' privileges (in the context of network access/Airflow roles) to achieve Remote Code Execution (RCE) on the webserver. The issue is resolved in version 3.2.0 by re-implementing validation for reserved serialization keys.

## Affected products

- Apache Airflow >= 3.1.8, < 3.2.0

## Identifiers

- CVE-2026-33858
- GHSA-mc4f-r875-v87w
- PYSEC-2026-20

## Timeline

- 2026-03-27: patched: Fix merged into main branch via PR #64148
- 2026-04-13: advisory: Initial disclosure and CVE assignment

## References

- [https://github.com/apache/airflow/pull/64148](https://github.com/apache/airflow/pull/64148)
- [https://lists.apache.org/thread/1npt3o2x81s0gw9tmfcv4n7p1z9hdmy0](https://lists.apache.org/thread/1npt3o2x81s0gw9tmfcv4n7p1z9hdmy0)
- [http://www.openwall.com/lists/oss-security/2026/04/13/7](http://www.openwall.com/lists/oss-security/2026/04/13/7)
- [https://github.com/pypa/advisory-database/tree/main/vulns/apache-airflow/PYSEC-2026-20.yaml](https://github.com/pypa/advisory-database/tree/main/vulns/apache-airflow/PYSEC-2026-20.yaml)

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