Executive brief
The Amazon EFS CSI Driver is a Kubernetes storage plugin that enables containerized applications to use Amazon EFS file systems. A vulnerability in its volume-deletion logic allows authenticated Kubernetes users with permission to create volumes to exploit a non-default configuration and cause the driver to recursively delete directories from EFS file systems they are not authorized to access, potentially resulting in data loss.
Technical details
CVE-2026-85781 is an insufficient validation vulnerability in the Amazon EFS CSI Driver's volume-deletion controller logic. When the non-default --delete-access-point-root-dir=true flag is enabled, the controller fails to verify that the EFS access point referenced in a PersistentVolume's volume handle actually belongs to the file system also referenced in that same volume handle. An authenticated Kubernetes user with create/delete PersistentVolume permissions can craft a malicious volume handle containing a valid access point from a different EFS file system, causing the controller to recursively delete directories from that unauthorized file system during volume deletion. The vulnerability requires specific configuration (the non-default flag must be set) and Kubernetes API access, but does not affect the underlying Amazon EFS access control mechanisms. Patches are expected in versions after 3.4.0.
Affected products
- Amazon EFS CSI Driver <=3.4.0
Timeline
- 2026-09-09: disclosed
- 2026-09-04: advisory: AWS Security Bulletin 2026-099-AWS published