Vulnerability · medium
Apache Airflow set_xcom skips reserved-key check (CVE-2026-111421)
Tier C · Keep an eye on it – Check if you’re affected
Who’s exposed: Airflow 3.0.0 through pre-3.4.0 deployments with Dag authors
Tier C because: Hits tech teams
Reach
Attack
Damage
Fix
Popular tool
What to do
- Upgrade Apache Airflow to 3.4.0 or later
The Brief
- Apache Airflow's Task Execution API stored task-written XCom values without the reserved-key check that is applied elsewhere.
- As a result, task-written XComs can instantiate airflow.* classes on the API server.
- Affected versions are Apache Airflow 3.0.0 before 3.4.0; the source rates severity as moderate.
Why it matters
Deployments of Apache Airflow 3.0.0 to before 3.4.0 can have the API server instantiate airflow.* classes from task-written XComs, so teams running those versions should upgrade.
The checklist behind the tier
Checklist · 2 of 10 yes
| Yes | Hits tech teams | Judgment: Airflow is a workflow orchestration tool that data and dev teams build with and run. |
| No | Core infrastructure | Judgment: a single orchestration framework, not core infrastructure nearly every team runs. |
| Yes | Popular tool | Judgment: Apache Airflow is a widely used mainstream data orchestration platform. |
| No | Exploited in the wild | Open Source Security: the advisory reports no observed attacks, only a flaw description. |
| No | Public exploit | Open Source Security: the advisory describes the flaw without stating that exploit code is published. |
| No | Remote, no login | Open Source Security: exploitation requires a Dag author's task, so credentials are needed. |
| No | Full takeover | Open Source Security: the description is truncated and does not state code execution or admin rights. |
| No | Secrets exposed | Open Source Security: no theft or exposure of credentials, configs or user data is reported. |
| No | Supply chain | Open Source Security: a flaw in task-written XCom handling, not a compromised package or pipeline. |
| No | No fix yet | Open Source Security: affected versions are 3.0.0 before 3.4.0, implying a fix in 3.4.0. |
The official record
From CVE.org, CISA’s Known Exploited Vulnerabilities catalog, FIRST EPSS and the GitHub Advisory Database. Where these answer a checklist fact, they win over the reporting.
- Exploited
- Not in CISA’s exploited catalog
Timeline
Vulnerability posted to oss-sec by Rahul Vats
Open Source Security
CVE-2026-111421: Apache Airflow: Execution API: set_xcom skips the reserved-key check, so task-written XComs instantiate airflow.* classes on the API server
Source
CVE-2026-111421: Apache Airflow: Execution API: set_xcom skips the reserved-key check, so task-written XComs instantiate airflow.* classes on the API server ↗ Open Source Security · 3h ago
First seen · 1 source · Full story page · How tiers are decided