Bug 2493576 (CVE-2026-13434)

Summary:	CVE-2026-13434 virt-controller-rhel9: kubevirt: kubevirt: Multus default-network annotation injection via unvalidated tenant networkName when ExternalNetResourceInjection is enabled
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	fdeutsch, oramraz, smullick, stirabos, thason
Target Milestone:	---	Keywords:	Security
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Hardware:	All
OS:	Linux
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Doc Text:	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).	Story Points:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
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Description OSIDB Bzimport 2026-06-26 15:15:32 UTC

A flaw was found in KubeVirt's network annotation generator. The tenant-supplied multus.networkName in a VMI spec is written verbatim into the launcher pod's v1.multus-cni.io/default-network annotation without input validation. When the ExternalNetResourceInjection Beta feature gate is enabled (off by default), no NAD lookup is performed to catch malformed values, and a tenant can inject a JSON-formatted NetworkSelectionElement array to attach the pod to arbitrary network attachments in any namespace with attacker-controlled IP and MAC addresses. This enables cross-namespace network access and service impersonation. The vulnerable code path was introduced with the ExternalNetResourceInjection feature gate in KubeVirt v1.8.0, first shipped in OpenShift Virtualization 4.21.