Description

Unverified ownership of a storage access point in the volume deletion component of the Amazon EFS CSI Driver before v3.4.1 might allow an authenticated Kubernetes user with PersistentVolume creation privileges to cause recursive deletion of directories on an EFS filesystem they are not authorized to access, via a crafted PersistentVolume volumeHandle that pairs an access point from one filesystem with a different target filesystem. To remediate this issue, users should upgrade to version v3.4.1.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "8.7",
  "pubDate": "2026-09-04T19:17:34.157Z",
  "pubdate": "2026-09-04T19:17:34.157Z",
  "executiveSummary": "The Amazon EFS CSI Driver contains a critical vulnerability related to unverified ownership of storage access points during volume deletion processes. This flaw allows an authenticated Kubernetes user possessing PersistentVolume (PV) creation privileges to trigger unauthorized recursive deletion of directory structures on an EFS filesystem. The vulnerability stems from insufficient validation logic within the driver's volume deletion component, which fails to verify that a provided access point is cryptographically or logically bound to the target filesystem. By manipulating the volumeHandle parameter, an attacker can misconfigure the deletion request to target an unintended EFS filesystem. The impact is significant, potentially leading to unauthorized data loss and filesystem corruption. The vulnerability affects versions of the Amazon EFS CSI Driver prior to v3.4.1. Mitigation requires an immediate upgrade to the patched version. Exploitation is limited to users with existing cluster privileges to define storage resources, representing a significant risk to data integrity within multi-tenant Kubernetes environments using shared EFS infrastructure.",
  "technicalDetails": "The root cause of this vulnerability lies in the improper verification of the volumeHandle attribute during the CSI driver's DeleteVolume request lifecycle. The Amazon EFS CSI Driver's volume deletion component expects a volumeHandle that maps to a specific EFS access point. However, the driver lacks a robust validation mechanism to confirm that the referenced access point resides on the intended filesystem specified in the request context.\nThe attack flow commences when an authenticated user with PersistentVolume (PV) creation permissions initiates a malicious request. An attacker can craft a specific volumeHandle that encapsulates an access point ID from one EFS filesystem while specifying a different, unauthorized EFS filesystem as the target. Because the driver performs insufficient checks regarding the ownership or logical cross-reference between these two entities, it proceeds to execute the deletion logic against the target filesystem.\nWhen the Amazon EFS CSI Driver triggers the underlying deletion routine, it interprets the payload as a command to remove the storage access point directory. If the path manipulation results in the driver targeting the root or a sub-directory of the unauthorized filesystem, the driver executes a recursive delete operation. This behavior is facilitated by the driver's permissions to interact with the EFS management API to perform cleanup operations.\nThis vulnerability is classified as an access control flaw. The attack does not require direct network access to the filesystem itself but relies on the driver's role-based access to the EFS management plane. Once the crafted request is processed, the filesystem's directory structure is traversed and removed, leading to severe data loss. The lack of strict ownership binding ensures that even if an attacker does not have direct IAM or filesystem-level access, they can utilize the driver's legitimate management interface to perform unauthorized destructive operations. The vulnerability affects all versions of the Amazon EFS CSI Driver earlier than v3.4.1, as these versions do not implement the necessary cross-resource validation checks to prevent such object misidentification."
}