{
"document": {
"acknowledgments": [
{
"names": [
"Ashutosh with skyhighsecurity"
]
}
],
"aggregate_severity": {
"namespace": "https://www.microsoft.com/en-us/msrc/security-update-severity-rating-system",
"text": "Critical"
},
"category": "csaf_security_advisory",
"csaf_version": "2.0",
"distribution": {
"text": "Public",
"tlp": {
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"url": "https://www.first.org/tlp/"
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},
"lang": "en-US",
"notes": [
{
"category": "general",
"text": "To determine the support lifecycle for your software, see the Microsoft Support Lifecycle: https://support.microsoft.com/lifecycle",
"title": "Additional Resources"
},
{
"category": "legal_disclaimer",
"text": "The information provided in the Microsoft Knowledge Base is provided \\\"as is\\\" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.",
"title": "Disclaimer"
},
{
"category": "general",
"text": "Required. The vulnerability documented by this CVE requires customer action to resolve.",
"title": "Customer Action"
}
],
"publisher": {
"category": "vendor",
"contact_details": "secure@microsoft.com",
"name": "Microsoft Security Response Center",
"namespace": "https://msrc.microsoft.com"
},
"references": [
{
"category": "self",
"summary": "CVE-2026-40402 Windows Hyper-V Elevation of Privilege Vulnerability - HTML",
"url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40402"
},
{
"category": "self",
"summary": "CVE-2026-40402 Windows Hyper-V Elevation of Privilege Vulnerability - CSAF",
"url": "https://msrc.microsoft.com/csaf/advisories/2026/msrc_cve-2026-40402.json"
},
{
"category": "external",
"summary": "Microsoft Exploitability Index",
"url": "https://www.microsoft.com/en-us/msrc/exploitability-index?rtc=1"
},
{
"category": "external",
"summary": "Microsoft Support Lifecycle",
"url": "https://support.microsoft.com/lifecycle"
},
{
"category": "external",
"summary": "Common Vulnerability Scoring System",
"url": "https://www.first.org/cvss"
}
],
"title": "Windows Hyper-V Elevation of Privilege Vulnerability",
"tracking": {
"current_release_date": "2026-05-12T07:00:00.000Z",
"generator": {
"date": "2026-05-13T17:58:07.520Z",
"engine": {
"name": "MSRC Generator",
"version": "1.0"
}
},
"id": "msrc_CVE-2026-40402",
"initial_release_date": "2026-05-12T07:00:00.000Z",
"revision_history": [
{
"date": "2026-05-12T07:00:00.000Z",
"legacy_version": "1",
"number": "1",
"summary": "Information published."
}
],
"status": "final",
"version": "1"
}
},
"product_tree": {
"branches": [
{
"branches": [
{
"category": "product_version_range",
"name": "<10.0.20348.5139",
"product": {
"name": "Windows Server 2022 <10.0.20348.5139",
"product_id": "4"
}
},
{
"category": "product_version",
"name": "10.0.20348.5139",
"product": {
"name": "Windows Server 2022 10.0.20348.5139",
"product_id": "11923"
}
}
],
"category": "product_name",
"name": "Windows Server 2022"
},
{
"branches": [
{
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"name": "<10.0.20348.5139",
"product": {
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},
{
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}
],
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},
{
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"name": "<10.0.22631.7079",
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}
},
{
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],
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{
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},
{
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}
],
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},
"vulnerabilities": [
{
"cve": "CVE-2026-40402",
"cwe": {
"id": "CWE-416",
"name": "Use After Free"
},
"notes": [
{
"category": "general",
"text": "Microsoft",
"title": "Assigning CNA"
},
{
"category": "faq",
"text": "An attacker who successfully exploited this vulnerability could gain SYSTEM privileges.",
"title": "What privileges could be gained by an attacker who successfully exploited this vulnerability?"
},
{
"category": "faq",
"text": "This issue allows a guest VM to force the Hyper-V host's kernel to read from an arbitrary, potentially invalid address. The contents of the address read would not be returned to the guest VM. In most circumstances, this would result in a denial of service of the Hyper-V host (bugcheck) due to reading an unmapped address. It is possible to read from a memory mapped device register corresponding to a hardware device attached to the Hyper-V host which may trigger additional, hardware device specific side effects that could compromise the Hyper-V host's security.",
"title": "Under what circumstances might this vulnerability be exploited other than as a denial of service attack against a Hyper-V host?"
},
{
"category": "faq",
"text": "In this case, a successful attack could be performed from a low privilege Hyper-V guest. The attacker could traverse the guest's security boundary to gain access to the Hyper-V host environment.",
"title": "According to the CVSS metric, a successful exploitation could lead to a scope change (S:C). What does this mean for this vulnerability?"
}
],
"product_status": {
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"11924",
"12242",
"12243"
],
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"2",
"3",
"4"
]
},
"references": [
{
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"url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40402"
},
{
"category": "self",
"summary": "CVE-2026-40402 Windows Hyper-V Elevation of Privilege Vulnerability - CSAF",
"url": "https://msrc.microsoft.com/csaf/advisories/2026/msrc_cve-2026-40402.json"
}
],
"remediations": [
{
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"date": "2026-05-12T07:00:00.000Z",
"details": "10.0.20348.5139:Security Update:https://support.microsoft.com/help/5087545",
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"3"
],
"url": "https://support.microsoft.com/help/5087545"
},
{
"category": "vendor_fix",
"date": "2026-05-12T07:00:00.000Z",
"details": "10.0.20348.5074:Security Hotpatch Update:https://support.microsoft.com/help/5087424",
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"4",
"3"
],
"url": "https://support.microsoft.com/help/5087424"
},
{
"category": "vendor_fix",
"date": "2026-05-12T07:00:00.000Z",
"details": "10.0.22631.7079:Security Update:https://support.microsoft.com/help/5087420",
"product_ids": [
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"1"
],
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}
],
"scores": [
{
"cvss_v3": {
"attackComplexity": "LOW",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 9.3,
"baseSeverity": "CRITICAL",
"confidentialityImpact": "HIGH",
"environmentalsScore": 0.0,
"exploitCodeMaturity": "UNPROVEN",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"remediationLevel": "OFFICIAL_FIX",
"reportConfidence": "CONFIRMED",
"scope": "CHANGED",
"temporalScore": 8.1,
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C",
"version": "3.1"
},
"products": [
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"2",
"3",
"4"
]
}
],
"threats": [
{
"category": "impact",
"details": "Elevation of Privilege"
},
{
"category": "exploit_status",
"details": "Publicly Disclosed:No;Exploited:No;Latest Software Release:Exploitation Less Likely"
}
],
"title": "Windows Hyper-V Elevation of Privilege Vulnerability"
}
]
}