CVE-2026-13208
Description
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.
Statement
Red Hat has assessed this issue as Moderate impact for OpenShift Virtualization. In a default deployment, a user with namespace edit permissions can exec into their own virt-launcher pod and exploit the unvalidated VMI identity in the notify server to disrupt co-located VMs belonging to other tenants. The attack is limited to denial of service (forced shutdown/restart of targeted VMs) and does not provide data access or code execution. Exploitation requires: (1) shell access inside a virt-launcher pod on the target node, (2) knowledge of the victim VMI's namespace and name, and (3) the victim VM to be scheduled on the same node. SELinux MCS labels do not mitigate this because the notify pipe socket is a legitimate communication channel accessible to the launcher process. Network policies are irrelevant as this uses local Unix sockets.
Mitigation
Organizations can reduce exposure by: (1) restricting pods/exec permission on virt-launcher pods via admission policies (e.g., Gatekeeper or Kyverno rules denying exec on pods with the kubevirt.io launcher label), (2) using node affinity or dedicated node pools to isolate high-security tenant workloads from untrusted tenants, and (3) monitoring for unexpected VMI state transitions via cluster alerting.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6.5 | N/A | N/A |
| Attack Vector | Local | N/A | N/A |
| Attack Complexity | Low | N/A | N/A |
| Privileges Required | Low | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Changed | N/A | N/A |
| Confidentiality | None | N/A | N/A |
| Integrity Impact | None | N/A | N/A |
| Availability Impact | High | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H
Red Hat CVSS v3 Score Explanation
AV:L - requires exec into own virt-launcher pod (local Unix socket access). AC:L - deterministic exploitation, connect to known socket path and send gRPC. PR:L - namespace edit role (standard tenant) provides pods/exec on own launcher. UI:N - no user interaction needed. S:C - attacker crosses namespace security boundary to disrupt other tenants' VMIs. C:N - no information disclosure. I:N - status spoofing is mechanism for DoS, not standalone integrity impact; transient and self-healing. A:H - complete disruption of targeted VMI lifecycle management (forced shutdown/restart loops).
Understanding the Weakness (CWE)
Integrity,Confidentiality,Availability,Access Control
Technical Impact: Read Application Data; Gain Privileges or Assume Identity; Execute Unauthorized Code or Commands
This weakness can lead to the exposure of resources or functionality to unintended actors, possibly providing attackers with sensitive information or even execute arbitrary code.
Acknowledgements
This issue was discovered by Huzaifa Sidhpurwala (Red Hat).
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