Bug 2492220 (CVE-2026-13208)

Summary: CVE-2026-13208 kubevirt: virt-handler-rhel9: kubevirt: virt-handler notify server trusts VMI identity from unauthenticated gRPC request body
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: fdeutsch, oramraz, smullick, stirabos, thason
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in KubeVirt's virt-handler domain notify server. The gRPC handlers for HandleDomainEvent and HandleK8SEvent derive the VMI identity (namespace/name) solely from the request body without validating it against the connection's origin. Each virt-launcher pod connects through a per-VMI pipe socket, but no identity tag is propagated from the pipe path to the server handlers. This allows a compromised virt-launcher process to send forged domain lifecycle events for any other VMI scheduled on the same node, causing virt-handler to erroneously update that VMI's state and disrupt its lifecycle management.
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Description OSIDB Bzimport 2026-06-24 15:04:59 UTC 
A flaw was found in KubeVirt's virt-handler domain notify server (pkg/virt-handler/notify-server/server.go). The gRPC handlers HandleDomainEvent (L54) and HandleK8SEvent (L96) derive the target VMI identity solely from the request body (DomainJSON informer key, EventNamespace/EventName) without validating it against the originating connection. Each virt-launcher connects via a per-VMI domain-notify-pipe.sock, but pipe.go performs a raw io.Copy byte pump with no peer identity tagging. No SO_PEERCRED or per-connection authentication is present on the shared socket.

A compromised virt-launcher can connect to its own pipe socket and send HandleDomainEvent/HandleK8SEvent gRPC messages claiming to be any other VMI on the same node. virt-handler processes these as authoritative, updating the victim VMI's state in the Kubernetes API. This enables cross-tenant denial of service: forced shutdown/restart loops, lifecycle state corruption, and K8s Event forgery.

Upstream fix recommendation: Tag each pipe connection with the VMI UID at accept time (the pipe socket path already encodes it) and pass that identity through to the notify-server handlers; reject any DomainEvent/K8sEvent whose embedded namespace/name/UID does not match the connection's tagged identity.

References:
- Vulnerable file: pkg/virt-handler/notify-server/server.go
- Pipe handler: pkg/virt-handler/notify-server/pipe.go