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Two path traversal vulnerabilities, CVE-2026-3864 in the Kubernetes NFS CSI driver and CVE-2026-3865 in the SMB CSI driver, allow attackers with persistentvolumes:create permission to escape intended subdirectory boundaries and access other tenants’ data on shared exports. The flaws stem from the drivers trusting attacker-controlled subDir values embedded in PersistentVolume.volumeHandle fields and relying on Go path handling in ways that did not enforce containment, enabling unauthorized read, write, modification, and deletion of files across shared NFS or SMB storage.
Researchers said the issue reflects a broader trust-boundary failure in Kubernetes environments, where requests that are authenticated and authorized by the API are not necessarily safe for privileged components to execute. In some NFS deployments with broader hostPath exposure, the bugs could also lead to arbitrary directory deletion on worker nodes. Fixes were released in NFS CSI Driver v4.13.1 and SMB CSI Driver v1.20.1, while defenders were urged to restrict PersistentVolume creation, tighten RBAC and GitOps service accounts, use admission controls to validate storage parameters, and review similar path-handling patterns across other CSI drivers and cloud-native components.
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Patched versions were made available as csi-driver-nfs v4.13.1 and csi-driver-smb v1.20.1 to address the two storage path traversal flaws. Coverage also recommended restricting PersistentVolume creation and adding admission-time validation to reduce similar abuse paths.
Security researchers disclosed CVE-2026-3864 in csi-driver-nfs and CVE-2026-3865 in csi-driver-smb, describing how attacker-controlled subDir values in PersistentVolume volumeHandle fields could bypass intended directory boundaries and enable cross-tenant access to shared storage.
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A **path traversal vulnerability** in the Kubernetes **CSI Driver for NFS** (`nfs.csi.k8s.io`) could allow attackers with permission to create `PersistentVolume` objects to supply crafted `volumeHandle` values containing `../` sequences in the `subDir` field. During deletion or cleanup operations, the driver may traverse outside the intended managed path and delete or modify unintended directories on the backing NFS server. The issue is tracked as **CVE-2026-3864** and carries a **CVSS 6.5** rating, with impact focused on integrity and availability rather than confidentiality. Affected deployments are those running **CSI Driver for NFS versions prior to `v4.13.1`** while allowing non-administrative or otherwise untrusted users to create PersistentVolumes that reference the NFS CSI driver. Kubernetes guidance says organizations should upgrade to **`v4.13.1` or later**, restrict PersistentVolume creation to trusted administrators, inspect `volumeHandle` values for traversal strings such as `../`, and review controller logs for unexpected directory operations such as references to paths escaping the intended export directory. This is a substantive vulnerability disclosure, not promotional or generic content.
Aug 6, 2026
Kubernetes maintainers disclosed five critical vulnerabilities in **ingress-nginx**, including **`CVE-2025-1974`** with a **CVSS 9.8** rating, warning that attackers on the Pod network could abuse configuration injection in the Validating Admission Controller to take over clusters without credentials. The flaws also affect how ingress-nginx builds **NGINX** configuration from crafted Ingress objects, potentially exposing Secrets available to the controller and leading to full cluster compromise. Patched releases **`ingress-nginx v1.12.1`** and **`v1.11.5`** were issued, and operators were urged to upgrade immediately or temporarily disable the Validating Admission Controller until patching is complete. The disclosure adds to broader concerns about Kubernetes networking and multi-tenant isolation, highlighted by **`CVE-2021-25740`**, an unpatchable issue that lets users with permission to modify **Endpoint** or **EndpointSlice** objects redirect service traffic to unauthorized IP addresses. In shared ingress-controller or load-balancer deployments, that behavior can allow one tenant to steer traffic into another tenant’s workloads and bypass intended network boundaries. Security researchers and vendors said the combined risk is highest in clusters that rely on shared ingress infrastructure with broad Secret access, and recommended tightening EndpointSlice permissions, avoiding shared ingress designs in sensitive environments, and evaluating the **Gateway API** as a safer architecture.
Jun 29, 2026
AWS disclosed **CVE-2026-6437**, a mount option injection vulnerability in the Amazon EFS CSI Driver that stems from insufficient input validation before user-controlled values are passed to the operating system's mount helper. In affected versions prior to `3.0.1`, Kubernetes `PersistentVolume` attributes including `mounttargetip` and `volumeHandle` can be crafted with injected comma-separated values that the Linux mount process interprets as additional mount options. Because the driver builds the mount option string directly from those fields and executes with elevated privileges on Kubernetes nodes, an attacker could cause unauthorized mount flags to be applied to the target EFS filesystem during the CSI driver's mount operation. The flaw affects environments using vulnerable EFS CSI Driver releases, and the reported remediation is to upgrade to version `3.0.1` or later.
Jun 29, 2026