CVE-2026-27211 Cloud Hypervisor: Host File Exfiltration via QCOW Backing File Abuse
A malicious guest can exfiltrate arbitrary host files by abusing QCOW2 backing file detection in Cloud Hypervisor when using writable or untrusted disk images.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-27211?
CVE-2026-27211 is a critical path traversal vulnerability in cloud-hypervisor, published on 21 Feb 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-73
Which versions are affected by CVE-2026-27211?
It affects 1 product.
Products include Cloudhypervisor Cloud Hypervisor.
How do I fix CVE-2026-27211?
Upgrade to a fixed version.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-27211 being exploited?
There is no known exploitation of CVE-2026-27211 in the wild and no public exploit code.
Other vulnerabilities in cloud-hypervisor
Sources
Also known as AZL-78282, GHSA-jmr4-g2hv-mjj6.