# CVE-2026-59242: Apache Airflow: Arbitrary airflow.* class instantiation on the API server via the XCom deserialize endpoint

Status: published. Published: 2026-08-12. Updated: 2026-11-03.

Apache Airflow's XCom `GET /api/v2/{...}/xcomEntries/{key}?deserialize=true` endpoint passed a string-literal payload through `BaseXCom.deserialize_value` without the `_check_forbidden_xcom_keys` guard, allowing an authenticated API user with XCom write-and-read access to instantiate arbitrary `airflow.*` classes on the API server (CWE-502). An authenticated user who can write an XCom value and then read it back with `deserialize=true` triggers the unsafe instantiation. Users are advised to upgrade to apache-airflow 3.3.1 or later, which rejects reserved XCom serialization keys submitted as JSON string literals.

## 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/69378

## Affected products and versions

- Apache Software Foundation / Apache Airflow (apache-airflow): ≥ 0; < 3.0.0 (affected, semver). Source: CNA: apache
- Apache Software Foundation / Apache Airflow (apache-airflow-core): ≥ 3.0.0; < 3.3.1 (affected, semver). Source: CNA: apache

## Severity and prioritization

- CVSS 3.1: 5.4 (medium); CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N; source: ADP: CISA-ADP

- CISA KEV: No listing in collected sources

- EPSS: 0.53% as of 2026-11-02; percentile 44.75%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- 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/69378 (CNA: apache; patch)

- https://lists.apache.org/thread/dm0520yhh4mn7qknyoh45r2w6c5qg2mg (CNA: apache; vendor-advisory)

- http://www.openwall.com/lists/oss-security/2026/08/12/6 (ADP: CVE)

## Provenance

- CNA: apache: https://www.cve.org/CVERecord?id=CVE-2026-59242; retrieved 2026-11-03; source updated 2026-11-03

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-59242; retrieved 2026-11-03; source updated Not reported

Revision: 6de2c10ece9a4847199d403e93e3fc42182638525f09baf818b03e6233687053

Canonical: https://y2.dev/cve/CVE-2026-59242

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