Cloud HypervisorApplication · Cloudhypervisor
CVE-2026-27211
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedCloud 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceCloud Hypervisor versions 34.0-50.0 contain a flaw in image format auto-detection where a malicious guest can overwrite a virtio-block disk header with a crafted QCOW2 structure pointing to sensitive host paths. Upon VM boot or disk scan, the hypervisor reads and serves the targeted host file contents to the guest, allowing arbitrary file exfiltration within process privilege constraints.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
Cloud HypervisorApplication
>= 34.0, < 50.1CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Changed
- Confidentiality
- High
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify installed Cloud Hypervisor versionRun `cloud-hypervisor --version` or check the binary package version installed via your system package managerAffected if Version is 34.0 through 50.0 (inclusive)
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Check if virtio-block disk devices are configuredReview VM configuration files or command-line arguments for virtio-block device definitions using --disk path=...Affected if Virtio-block disks are attached to the VM without additional read-only or integrity safeguards
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Determine if QCOW2 image format is in use with auto-detectionInspect VM disk configuration for QCOW2 backing files or format=qcow2 parameters; Cloud Hypervisor auto-detects format when not explicitly specifiedAffected if Disks use QCOW2 format with auto-detection enabled (format not explicitly set to a fixed value)
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Verify disk backing image permissions and originCheck the ownership and permissions of QCOW2 backing image files referenced in disk configuration; confirm if they are marked read-only and sourced from trusted locationsAffected if Backing images lack read-only flag or originate from untrusted or writable locations
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Check if landlock sandboxing is activeInspect process privileges or hypervisor launch parameters for landlock enforcement; verify if restricted process privileges are in placeAffected if Landlock sandboxing is disabled and the hypervisor runs with full process privileges
Your environment is affected if Cloud Hypervisor version is between 34.0 and 50.0, you use virtio-block disks with QCOW2 auto-detection, and backing images are not read-only or from trusted sources.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped50.1
Upgrade to version 50.1 or enable land lock sandboxing with restricted process privileges. Ensure backing images are read-only and sourced from trusted origins.
50.1
- Obtain Cloud Hypervisor version 50.1 or later from the official GitHub releases or package repository
- Stop all running Cloud Hypervisor instances
- Backup your current Cloud Hypervisor configuration and any custom scripts
- Install Cloud Hypervisor version 50.1 following your deployment method (source build, package manager, or binary)
- Verify the upgrade was successful by running `cloud-hypervisor --version` and confirming it reports 50.1 or later
- Restart your VMs and verify normal operation
- If using virtio-block devices with raw image backends, ensure the backing images are either read-only or from trusted sources
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Cloud Hypervisor
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,600.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-27211 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-27211 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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