# CVE-2026-40861: Apache Airflow: Arbitrary File Read via Log Symlink following in FileTaskHandler

Status: published. Published: 2026-06-01. Updated: 2026-11-03.

A Dag author could either (a) create a symlink under their task's log directory pointing to an arbitrary file readable by the API server process (read-path attack — e.g. `/etc/passwd` or `airflow.cfg`) or (b) supply a `task_id` containing `..` sequences accepted by the Task SDK's `KEY_REGEX` (write-path attack), and in both cases the FileTaskHandler resolves the log path outside the configured `base_log_folder`, leaking or overwriting arbitrary files. Only affects deployments where the worker log folder is shared with the API server. Users are advised to upgrade to `apache-airflow` 3.2.2 or later. As a defense-in-depth mitigation, deploy the worker and API server with separate log volumes so that worker-controlled paths cannot reach the API server's filesystem.

## 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/65325

## 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; < 3.2.2 (affected, semver). Source: CNA: apache

## Severity and prioritization

- CVSS 3.1: 6.5 (medium); CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N; source: ADP: CISA-ADP

- CISA KEV: No listing in collected sources

- EPSS: 0.69% as of 2026-11-02; percentile 52.85%

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

- Weaknesses: CWE-59

## Exploit evidence

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

## References

- https://github.com/apache/airflow/pull/65325 (CNA: apache; patch)

- https://lists.apache.org/thread/823334db2559xjlwt59gpzjz47thnscl (CNA: apache; vendor-advisory)

- http://www.openwall.com/lists/oss-security/2026/05/31/1 (ADP: CVE)

## Provenance

- CNA: apache: https://www.cve.org/CVERecord?id=CVE-2026-40861; retrieved 2026-11-03; source updated 2026-11-03

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-40861; retrieved 2026-11-03; source updated Not reported

Revision: f42b86186f0126fd45c5ac40a44fa3d7493ebc07e842ad6aef6a39f2b06ba03c

Canonical: https://y2.dev/cve/CVE-2026-40861

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