CVE-2026-103505 in aws-efs-csi-driver
Summary
by MITRE • 10/01/2026
Improper neutralization of argument delimiters in the volume handling component in AWS EFS CSI Driver (aws-efs-csi-driver) v3.1.0 through v3.4.2 might allow remote authenticated users with PersistentVolume creation permissions to inject arbitrary mount options via comma-separated values in the mounttargetipmap volumeAttribute.
To remediate this issue, users should upgrade to version v3.5.0 or later.
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Analysis
by VulDB Data Team • 10/01/2026
The vulnerability identified within AWS Elastic File System Container Storage Interface driver versions 3.1.0 through 3.4.2 represents a critical input validation failure in the volume handling subsystem. This flaw stems from improper neutralization of argument delimiters, specifically affecting how mount target IP addresses are processed when constructing storage volumes for Kubernetes workloads. The core technical issue lies in the parsing logic that handles comma-separated values within the mounttargetipmap volume attribute. In standard Linux filesystem mounting operations, commas serve as delimiters to separate multiple options passed to the mount command or related system calls. However, the affected driver versions fail to adequately sanitize or escape these characters when they appear within user-supplied input fields intended solely for IP address specification. This lack of strict validation allows an attacker who can control this specific attribute to inject additional arguments that are interpreted as valid mount options rather than being treated as part of the target identifier.
From a technical perspective, this vulnerability is classified under CWE-77: Improper Neutralization of Special Elements used in a Command which aligns with command injection patterns where special characters bypass intended parsing boundaries. The operational impact is significant for environments utilizing AWS EFS CSI Driver to manage persistent storage for containerized applications. An attacker who possesses the necessary permissions to create PersistentVolumes, such as those granted through Kubernetes Role-Based Access Control policies like PersistentVolume creation rights, can exploit this flaw to manipulate how the underlying file system is mounted on the node hosting the pod. By injecting arbitrary mount options via comma-separated values in the specified attribute, an adversary could potentially alter security-related parameters of the mount operation. This might include disabling strict noexec or nosuid flags, changing ownership permissions, or enabling other filesystem behaviors that deviate from the cluster administrator's intended configuration.
The exploitation scenario typically involves a compromised application account or a misconfigured service account with elevated storage creation privileges interacting with the Kubernetes API server to submit a PersistentVolumeClaim and associated volume definition containing the maliciously crafted mounttargetipmap value. Once processed by the vulnerable driver version, this input propagates down to the node-level agent responsible for executing the actual mount commands against the AWS EFS infrastructure. The resulting misconfiguration could lead to privilege escalation within the container runtime environment if security boundaries are weakened, or it may facilitate data exfiltration and lateral movement by exposing sensitive volumes with overly permissive access controls that were not originally intended by the system administrator. This aligns with MITRE ATT&CK technique T1608: Install Remote Tool, as weakening mount restrictions can allow for easier deployment of malicious binaries or scripts on the host node through mounted volumes.
To mitigate this risk, organizations must immediately upgrade the AWS EFS CSI Driver to version 3.5.0 or any subsequent release where these input validation checks have been hardened. The patched versions implement stricter parsing rules that ensure only valid IP address formats are accepted for the mount target attributes, effectively neutralizing the ability of attackers to inject delimiter characters into command arguments. In addition to upgrading software components, administrators should review and restrict RBAC policies within their Kubernetes clusters to adhere to the principle of least privilege. This involves ensuring that only trusted service accounts have permissions to create PersistentVolumes or modify storage class configurations. Regular auditing of these permissions helps reduce the attack surface available for exploitation by compromised identities or insider threats seeking to manipulate infrastructure components through API-level interactions.