CVE-2026-40861

CVE-2026-40861 is a medium-severity vulnerability in Apache Airflow with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-59.

Key facts

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.

Frequently asked questions

What is CVE-2026-40861?
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.
How severe is CVE-2026-40861?
CVE-2026-40861 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2026-40861 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (47th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-40861?
CVE-2026-40861 affects Apache Airflow. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-40861?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-40861 have an EU (EUVD) identifier?
Yes. CVE-2026-40861 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-33598.
When was CVE-2026-40861 published?
CVE-2026-40861 was published on 2026-06-01 and last updated on 2026-06-17.

References

Affected products (1)

More vulnerabilities in Apache Airflow

All CVEs affecting Apache Airflow →

Other CWE-59 (Improper Link Resolution Before File Access (Link Following)) vulnerabilities

Browse all CWE-59 (Improper Link Resolution Before File Access (Link Following)) vulnerabilities →