What is the CVSS score of CVE-2026-27211?

CVE-2026-27211 has a CVSS 3.1 base score of 10.0 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N. EPSS exploitation probability: 0.0%.

How to fix or mitigate CVE-2026-27211?

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. Within 30 days: Validate patch deployment across infrastructure, conduct log review for exploitation attempts, and implement post-incident security controls.

Cloud Hypervisor CVE-2026-27211

CRITICAL

External Control of File Name or Path (CWE-73)

2026-02-21 security-advisories@github.com

Information Disclosure Linux Docker Path Traversal Kubernetes KVM Cloud Hypervisor

10.0

CVSS 3.1 · GitHub Advisory

View

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

Access

Malicious guest overwrites disk header
Delivery

Craft QCOW2 structure pointing to host path
Exploit

Trigger VM reboot or disk scan
Execution

Auto-detection parses crafted header
Impact

Exfiltrate sensitive host files

Vulnerability Assessment

Weakness	CWE CWE-73 OWASP Top 10:2025 A06:2025 - Insecure Design ASVS 5.0 V5 - File Handling File name/path control
Exploitation Conditions	Virtio-block devices backed by raw images must be configured for Cloud Hypervisor VMs (versions 34.0-50.0). Image format auto-detection enabled on disk scan/VM boot. Guest must have write access to disk header.
Impact	CVSS 10.0. Cloud Hypervisor VM escape — host file theft.
Exploit ScenarioDerived	Guest VM reads arbitrary files from the host system.

Act Now Prioritize within 24-48h. Why: CRITICAL severity.

Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

Arbitrary host file exfiltration from Cloud Hypervisor VMM versions 34.0-50.0. CVSS 10.0. Patch available.

Earlier versions of this analysis (1)

v1 Mar 12, 2026 - 22:04 CVSS 10.0

VM escape file exfiltration in Cloud Hypervisor.

RemediationAI

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Technical ContextAI · show details

CWE-73 file path control.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

GitHub Advisory PRIMARY 10.0 CRITICAL

AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Changed

Confidentiality

High

Integrity

High

Availability

None

Lifecycle Timeline

Patch released

Feb 24, 2026 - 17:08 nvd

Patch available

CVE Published

Feb 21, 2026 - 06:17 nvd

CRITICAL 10.0

DescriptionGitHub Advisory

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.

Executive ViewAI

Why It Matters

Cloud Hypervisor versions 34.0-50.0 contain a critical vulnerability allowing attackers to extract arbitrary files from host systems when using virtio-block storage devices. Organizations running affected versions face immediate risk of sensitive data exposure, including credentials, proprietary information, and system configurations stored on hypervisor hosts.

Business Impact: Severe

Compensating Controls

Apply vendor patch.

Threat Intelligence Overview

EPSS Score

0.0%

Top 85% exploitable

Data Quality

4 sources

Confidence: Medium

NVD

CVE.org

EPSS

GitHub

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity CRITICAL

CISA KEV No

Public POC No

EPSS 0.0%

Patch available Yes

Active threat No

Deciding rule

CRITICAL severity

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Out-of-Cycle

Exploitation· derived

None

System Exposure· derived

Open

Automatable· derived

Yes

Human Impact

Very High

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +50

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Path Traversal HIGH

Path traversal exploits occur when applications use user-controlled input to construct file system paths without proper validation.

Information Disclosure MEDIUM

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.