# CVE-2026-33264: Apache Airflow: DAG author RCE on webserver via unrestricted import_string() in BaseSerialization.deserialize()

Status: published. Published: 2026-07-07. Updated: 2026-11-03.

A bug in `BaseSerialization.deserialize()` allowed unrestricted `import_string()` of attacker-controlled class paths when the Scheduler / API Server loaded a serialized DAG: a DAG author could embed a malicious trigger into a DAG to gain remote code execution on the API Server / Scheduler process, crossing the Airflow security boundary that DAG-author code must never execute in those processes. Users are advised to upgrade to `apache-airflow` 3.3.0 or later. As a defense-in-depth mitigation, deployments where DAG-author trust is limited can restrict the `[core] allowed_deserialization_classes` config to a narrow allowlist.

## 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/66002
- 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/68528

## 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; < 3.3.0 (affected, semver). Source: CNA: apache

## Severity and prioritization

- CVSS 3.1: 9.8 (critical); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H; source: ADP: CISA-ADP

- CISA KEV: No listing in collected sources

- EPSS: 1.65% as of 2026-11-02; percentile 76.49%

- SSVC: exploitation none; automatable yes; technical impact total; 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/66002 (CNA: apache; patch)

- https://github.com/apache/airflow/pull/68528 (CNA: apache; patch)

- https://lists.apache.org/thread/otvdw8qt2y7xy2n5nq9xby9ky4rf5ltj (CNA: apache; vendor-advisory)

- http://www.openwall.com/lists/oss-security/2026/07/07/1 (ADP: CVE)

## Provenance

- CNA: apache: https://www.cve.org/CVERecord?id=CVE-2026-33264; retrieved 2026-11-03; source updated 2026-11-03

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-33264; retrieved 2026-11-03; source updated Not reported

Revision: d27e998094e5cb258c3a31f8ea452e2111ac937e5fc7ce333b4ba3bf9ff75465

Canonical: https://y2.dev/cve/CVE-2026-33264

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