CVE-2026-40861: apache software foundation apache airflow Link Following

Vulnerability summary

CVE-2026-40861 is a medium (CVSS 6.5) Link Following vulnerability in apache software foundation apache airflow. EPSS estimates a 0.76% chance of exploitation in the next 30 days, higher than 54.4% of scored vulnerabilities.

Timeline

1. 01-06-2026
   PublishedVulnerability first disclosed.
2. 02-06-2026
   Last modifiedVulnerability information updated.

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.

• CWE-59Improper Link Resolution Before File Access ('Link Following')The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.