CVE-2026-27211
CRITICALCVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N
Lifecycle Timeline
3Description
Cloud Hypervisor is a Virtual Machine Monitor for Cloud workloads. Versions 34.0 through 50.0 arevulnerable to arbitrary host file exfiltration (constrained by process privileges) when using virtio-block devices backed by raw images. A malicious guest can overwrite its disk header with a crafted QCOW2 structure pointing to a sensitive host path. Upon the next VM boot or disk scan, the image format auto-detection parses this header and serves the host file's contents to the guest. Guest-initiated VM reboots are sufficient to trigger a disk scan and do not cause the Cloud Hypervisor process to exit. Therefore, a single VM can perform this attack without needing interaction from the management stack. Successful exploitation requires the backing image to be either writable by the guest or sourced from an untrusted origin. Deployments utilizing only trusted, read-only images are not affected. This issue has been fixed in version 50.1. To workaround, enable land lock sandboxing and restrict process privileges and access.
Analysis
Arbitrary host file exfiltration from Cloud Hypervisor VMM versions 34.0-50.0. CVSS 10.0. …
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Remediation
Within 24 hours: Inventory all Cloud Hypervisor deployments and identify instances running versions 34.0-50.0; assess whether virtio-block devices with raw image backing are in use. Within 7 days: Apply available vendor patches to all affected systems during maintenance windows, prioritizing production environments. …
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