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

[Rahul Vats <rahulvats () apache org>]

Severity: low 

Affected versions:

- Apache Airflow (apache-airflow) before 3.2.2

Description:

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.

Credit:

Silas Boch (finder)
Lakshmikanthan K (letchupkt) (finder)
Jarek Potiuk (remediation developer)

References:

https://github.com/apache/airflow/pull/65325
https://airflow.apache.org/
https://www.cve.org/CVERecord?id=CVE-2026-40861