# 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

Status: published. Published: 2026-11-09. Updated: 2026-11-09.

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.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: apache) — https://github.com/apache/airflow/pull/72718
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: apache) — https://github.com/apache/airflow/pull/74829

## Affected products and versions

- Apache Software Foundation / Apache Airflow (apache-airflow-core): ≥ 3.0.0; < 3.4.0 (affected, semver). Source: CNA: apache

## Severity and prioritization

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-502

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/apache/airflow/pull/72718 (CNA: apache; patch)

- https://github.com/apache/airflow/pull/74829 (CNA: apache; patch)

- https://www.cve.org/CVERecord?id=CVE-2026-59242 (CNA: apache; related)

- https://lists.apache.org/thread.html/pwdwx354tv0x3m8wzfhh59r6wyztj2lk (CNA: apache; vendor-advisory)

## Provenance

- CNA: apache: https://www.cve.org/CVERecord?id=CVE-2026-111421; retrieved 2026-11-09; source updated 2026-11-09

Revision: 0ca9769cf6076677a5353ccc43cd09e053f10815b2e3e69a41d574fdac1ddd81

Canonical: https://y2.dev/cve/CVE-2026-111421

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