KubeVirt v1.8.0 Network Annotation Injection Allows Cross-namespace Impersonation
CVE-2026-13434 Published on June 26, 2026

Virt-controller-rhel9: kubevirt: kubevirt: multus default-network annotation injection via unvalidated tenant networkname when externalnetresourceinjection is enabled
A flaw was found in KubeVirt's network annotation generator. When a tenant creates a VirtualMachineInstance with a Multus network configuration, the supplied networkName value is written verbatim into the launcher pod's v1.multus-cni.io/default-network annotation without format validation or sanitization. The only admission check rejects empty strings; no DNS-1123 format validation, JSON detection, or special character rejection is performed. When the ExternalNetResourceInjection Beta feature gate is enabled (off by default, cluster-admin only), the NAD lookup that would otherwise catch malformed names is skipped by design. A tenant with kubevirt.io:edit permissions can inject a JSON-formatted NetworkSelectionElement array specifying an arbitrary namespace, NAD name, static IP address, and MAC address. Multus on the node parses this JSON and attaches the launcher pod to the specified network attachment in any namespace, enabling cross-namespace network access and IP/MAC impersonation on network segments normally segregated from tenant workloads. The ExternalNetResourceInjection feature gate was introduced in KubeVirt v1.8.0 (first shipped in OpenShift Virtualization 4.21).

NVD

Vulnerability Analysis

CVE-2026-13434 is exploitable with network access, and requires small amount of user privileges. This vulnerability is consided to have a high level of attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality and integrity, and no impact on availability.

Attack Vector:
NETWORK
Attack Complexity:
HIGH
Privileges Required:
LOW
User Interaction:
NONE
Scope:
CHANGED
Confidentiality Impact:
LOW
Integrity Impact:
LOW
Availability Impact:
NONE

Timeline

Reported to Red Hat.

Made public.

Weakness Type

Improper Input Validation

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.


Products Associated with CVE-2026-13434

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Red Hat Container Native Virtualization
 

Affected Versions

Red Hat OpenShift Virtualization 4: