AWS patches mount option injection flaw in EFS CSI Driver

Amazon Web Services has issued a security bulletin addressing a vulnerability in its Amazon Elastic File System (EFS) Container Storage Interface (CSI) Driver. The flaw, identified as CVE-2026-6437, involves mount option injection, which could compromise the integrity of file system mounts within Kubernetes environments.

According to the official advisory from AWS Security Bulletins, the vulnerability exists in the way the EFS CSI Driver handles mount options. An attacker with sufficient privileges within a Kubernetes cluster could potentially exploit this flaw to inject arbitrary mount options. This type of injection can lead to unauthorized access to sensitive data or the modification of file system behaviors, undermining the security controls intended by the cluster administrator.

Context and background

The EFS CSI Driver is a critical component for organizations using Amazon EFS with Kubernetes. It allows containers to dynamically provision and attach EFS volumes, enabling persistent storage for stateful applications. Because the driver operates with elevated privileges to manage volume attachments, vulnerabilities within its codebase can have significant security implications.

Mount option injection vulnerabilities occur when an application fails to properly sanitize user-supplied input that is later used in system commands or configuration files. In the context of a CSI Driver, this means that if a user or a compromised pod can influence the mount options passed to the underlying Linux mount command, they may be able to bypass security restrictions. For example, an attacker might inject options that disable access controls or map sensitive host directories into the container namespace.

AWS has a history of regularly patching vulnerabilities in its infrastructure components. The release of this bulletin indicates that the company has identified the risk and is providing guidance to mitigate it. While the specific technical details of the exploit are not fully elaborated in the summary, the classification of the issue as a mount option injection suggests a high-risk scenario for cloud-native environments.

Who is affected

Organizations using Amazon EFS with Kubernetes are affected by this vulnerability. Specifically, any workload that utilizes the EFS CSI Driver to mount file systems is potentially at risk. This includes a wide range of industries that rely on scalable, shared storage for their containerized applications.

The impact is most severe for environments where the principle of least privilege is not strictly enforced. If a user has the ability to create or modify PersistentVolumeClaims (PVCs) or StorageClasses that interact with the EFS CSI Driver, they may be able to trigger the vulnerability. Additionally, multi-tenant Kubernetes clusters are at higher risk, as a compromised tenant could potentially affect other tenants sharing the same storage infrastructure.

What should you do?

AWS has released an official security bulletin regarding CVE-2026-6437. Users should review the bulletin for specific remediation steps. Generally, this involves updating the EFS CSI Driver to a patched version. Until the update is applied, administrators should restrict permissions for creating and modifying storage resources to trusted users and service accounts only.

What to do and how to stay safe: AWS

• Update the Amazon EFS CSI Driver to the latest version that includes the fix for CVE-2026-6437, once the vendor provides an update.
• Audit Kubernetes RBAC policies to ensure that only authorized users and service accounts can create or modify PersistentVolumeClaims and StorageClasses.
• Monitor Kubernetes audit logs for unusual mount activities or attempts to inject unexpected parameters into storage configurations.
• Review existing EFS access points and policies to ensure they align with the principle of least privilege, limiting unnecessary access to sensitive data.

Step-by-step guide: Risk Based Vulnerability Management: Prioritize Fixes by Actual Threat

General security guidance from the Threat Times newsroom. It is not confirmed advice from the organisations named in this story.

Frequently asked questions

What is CVE-2026-6437?

CVE-2026-6437 is a mount option injection vulnerability in the Amazon EFS CSI Driver, as identified in the AWS security bulletin.

Who is affected by this vulnerability?

Organizations using Amazon EFS with Kubernetes and the EFS CSI Driver are affected by this vulnerability.

Is there a fix available?

AWS has issued a security bulletin for CVE-2026-6437, indicating that a fix or mitigation guidance is available through their official channels.