CVE-2026-13318
Description
A server-side request forgery (SSRF) flaw was found in KubeVirt's virt-api port-forward handler. When processing a port-forward request to a VirtualMachineInstance (VMI), virt-api reads the target IP from vmi.Status.Interfaces[0].IP and passes it directly to net.Dial() without validation. For VMIs using non-masquerade network bindings (bridge or secondary-only), this IP is reported by the QEMU guest agent running inside the VM and is fully controllable by the VM owner. An attacker with kubevirt.io:edit permissions can create a VM with a modified guest agent that reports an arbitrary IP address, then request port-forward to establish a bidirectional TCP tunnel from virt-api's cluster-internal network position to any routable destination, bypassing NetworkPolicy isolation.
Statement
Red Hat has rated this issue as Moderate impact. Only VMs configured with bridge binding or secondary-only network interfaces (which require a cluster administrator to have created a NetworkAttachmentDefinition) are affected.
Mitigation
Users who do not use bridge binding or secondary-only network interfaces for their VMs are not affected by this vulnerability. For environments using these configurations, cluster administrators can apply egress NetworkPolicy to the openshift-cnv namespace to restrict virt-api's outbound connections to known-legitimate destinations (launcher pod CIDRs and node IPs), which blocks the SSRF to arbitrary targets.
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 | 6.4 | N/A | N/A |
| Attack Vector | Network | 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 | Low | N/A | N/A |
| Integrity Impact | Low | N/A | N/A |
| Availability Impact | None | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
Red Hat CVSS v3 Score Explanation
AC:H — requires non-default bridge/secondary-only network binding (cluster-admin must create a NetworkAttachmentDefinition); default masquerade config is not vulnerable. S:C — virt-api dials targets under different security authorities (other pods/services/NetworkPolicy domains). C:L/I:L — bidirectional tunnel but no credentials forwarded; most internal services require mTLS/token auth.
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Application Data
Integrity
Technical Impact: Execute Unauthorized Code or Commands
Access Control
Technical Impact: Bypass Protection Mechanism
By providing URLs to unexpected hosts or ports, attackers can make it appear that the server is sending the request, possibly bypassing access controls such as firewalls that prevent the attackers from accessing the URLs directly. The server can be used as a proxy to conduct port scanning of hosts in internal networks, use other URLs such as that can access documents on the system (using file://), or use other protocols such as gopher:// or tftp://, which may provide greater control over the contents of requests.
Acknowledgements
This issue was discovered by Huzaifa Sidhpurwala (Red Hat).
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
