---
id: "CVE-2026-111421"
page: "https://infrastack.ai/live/CVE-2026-111421"
kind: "vulnerability"
aliases: ["CVE-2026-111421"]
title: "Apache Airflow: task-written XComs can make the API server instantiate arbitrary airflow classes"
severity: "high"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: [{"name": "apache-airflow", "fixed": [], "affected": "", "ecosystem": "pypi"}]
ecosystems: ["pypi"]
tags: ["apache-airflow", "python", "runtime", "self-hosted"]
not_affected_if: ["deserialization-disabled", "trusted-dag-authors"]
published_at: "2026-11-09T10:17:03+00:00"
first_seen_at: "2026-11-09T10:25:48+00:00"
updated_at: "2026-11-09T10:26:51+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-111421", "first_seen_at": "2026-11-09T10:25:48+00:00"}]
exploit_sources: []
---

# Apache Airflow: task-written XComs can make the API server instantiate arbitrary airflow classes

Link for people: https://infrastack.ai/live/CVE-2026-111421 (this .md is for agents)

A Dag author's task could write a crafted XCom value that, when viewed through the Airflow API with deserialization enabled, makes the API server instantiate classes from the airflow.* namespace with attacker-chosen arguments. This is an incomplete fix for CVE-2026-59242, and apache-airflow 3.3.1 users who applied that fix remain exposed.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- pypi:apache-airflow affected range not listed fixed no fixed version listed

## How to check

- Check the installed version with `airflow version` or `pip show apache-airflow`, and see whether it is `3.3.1` or earlier in the 3.x line.
- Confirm whether XCom deserialization is enabled on the API server (the sources do not name the setting; unknown).

## Fix

- apache-airflow: upgrade to `3.4.0` or later

## Timeline

- 2026-11-09T10:25:48+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-111421

## From the sources

Apache Airflow's Task Execution API stored XCom values written by a task without the reserved-key check applied elsewhere, so a Dag author's task could write an XCom that, when a user later viewed it through the API with deserialization enabled, made the API server instantiate classes from the `airflow.*` namespace with arguments the Dag author chose. This is an incomplete fix for CVE-2026-59242: users who applied that fix in apache-airflow 3.3.1 remain affected through this route and should upgrade to apache-airflow 3.4.0 or later.

---

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