Vulnerability-Lookup

MSRC_CVE-2026-21255

Vulnerability from csaf_microsoft - Published: 2026-02-10 08:00 - Updated: 2026-02-10 08:00

Summary

Windows Hyper-V Security Feature Bypass Vulnerability

Severity

Important

Notes

Additional Resources: To determine the support lifecycle for your software, see the Microsoft Support Lifecycle: https://support.microsoft.com/lifecycle

Disclaimer: 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.

Customer Action: Required. The vulnerability documented by this CVE requires customer action to resolve.

CVE-2026-21255

8.8 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C

CWE-284 - Improper Access Control

Vendor Fix 10.0.28000.1575:Security Update:https://support.microsoft.com/help/5077179 https://support.microsoft.com/help/5077179

Vendor Fix 10.0.17763.8389:Security Update:https://support.microsoft.com/help/5075904 https://support.microsoft.com/help/5075904

Vendor Fix 10.0.20348.4773:Security Update:https://support.microsoft.com/help/5075906 https://support.microsoft.com/help/5075906

Vendor Fix 10.0.20348.4711:Security Hotpatch Update:https://support.microsoft.com/help/5075943 https://support.microsoft.com/help/5075943

Vendor Fix 10.0.19044.6937:Security Update:https://support.microsoft.com/help/5075912 https://support.microsoft.com/help/5075912

Vendor Fix 10.0.19045.6937:Security Update:https://support.microsoft.com/help/5075912 https://support.microsoft.com/help/5075912

Vendor Fix 10.0.26100.32370:Security Update:https://support.microsoft.com/help/5075899 https://support.microsoft.com/help/5075899

Vendor Fix 10.0.26100.32313:Security Hotpatch Update:https://support.microsoft.com/help/5075942 https://support.microsoft.com/help/5075942

Vendor Fix 10.0.26200.7840:Security Update:https://support.microsoft.com/help/5077181 https://support.microsoft.com/help/5077181

Vendor Fix 10.0.26200.7781:Security Hotpatch Update:https://support.microsoft.com/help/5077212 https://support.microsoft.com/help/5077212

Vendor Fix 10.0.22631.6649:Security Update:https://support.microsoft.com/help/5075941 https://support.microsoft.com/help/5075941

Vendor Fix 10.0.25398.2149:Security Update:https://support.microsoft.com/help/5075897 https://support.microsoft.com/help/5075897

Vendor Fix 10.0.26100.7840:Security Update:https://support.microsoft.com/help/5077181 https://support.microsoft.com/help/5077181

Vendor Fix 10.0.26100.7781:Security Hotpatch Update:https://support.microsoft.com/help/5077212 https://support.microsoft.com/help/5077212

Vendor Fix 10.0.26100.7840:Security Update:https://support.microsoft.com/help/5077181 https://support.microsoft.com/help/5077181

Vendor Fix 10.0.14393.8868:Security Update:https://support.microsoft.com/help/5075999 https://support.microsoft.com/help/5075999

References

URL

Category

	https://msrc.microsoft.com/update-guide/vulnerabi…	self
	https://msrc.microsoft.com/csaf/advisories/2026/m…	self
	https://www.microsoft.com/en-us/msrc/exploitabili…	external
	https://support.microsoft.com/lifecycle	external
	https://www.first.org/cvss	external
	https://msrc.microsoft.com/update-guide/vulnerabi…	self
	https://msrc.microsoft.com/csaf/advisories/2026/m…	self

Acknowledgments

Sai Ganesh Ramachandran with Microsoft

JSON

To clipboard

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      "notes": [
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          "category": "general",
          "text": "Microsoft",
          "title": "Assigning CNA"
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        {
          "category": "faq",
          "text": "An attacker who successfully exploited this vulnerability could bypass the Virtualization-based Security feature.",
          "title": "What kind of security feature could be bypassed by successfully exploiting this vulnerability?"
        },
        {
          "category": "faq",
          "text": "Exploitation requires an attacker who already has local execution on a VBS\u2011enabled guest VM to run a specially crafted application or driver that abuses the hypervisor\u2019s overlay handling to bypass VBS/VTL protections and compromise kernel integrity.",
          "title": "How could an attacker exploit this vulnerability?"
        },
        {
          "category": "faq",
          "text": "An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.",
          "title": "According to the CVSS metric, a successful exploitation could lead to a scope change (S:C). What does this mean for this vulnerability?"
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          "4",
          "5",
          "6",
          "7",
          "8",
          "9",
          "10",
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            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "environmentalsScore": 0.0,
            "exploitCodeMaturity": "UNPROVEN",
            "integrityImpact": "HIGH",
            "privilegesRequired": "LOW",
            "remediationLevel": "OFFICIAL_FIX",
            "reportConfidence": "CONFIRMED",
            "scope": "CHANGED",
            "temporalScore": 7.7,
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C",
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      "threats": [
        {
          "category": "impact",
          "details": "Security Feature Bypass"
        },
        {
          "category": "exploit_status",
          "details": "Publicly Disclosed:No;Exploited:No;Latest Software Release:Exploitation Less Likely"
        }
      ],
      "title": "Windows Hyper-V Security Feature Bypass Vulnerability"
    }
  ]
}

CVE-2026-21255 (GCVE-0-2026-21255)

Vulnerability from cvelistv5 – Published: 2026-02-10 17:51 – Updated: 2026-04-10 13:21

Title

Windows Hyper-V Security Feature Bypass Vulnerability

Summary

Improper access control in Windows Hyper-V allows an authorized attacker to bypass a security feature locally.

Severity ?

8.8 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C

CWE

CWE-284 - Improper Access Control

Assigner

microsoft

References

URL

Tags

https://msrc.microsoft.com/update-guide/vulnerabi…

vendor-advisorypatch

Impacted products

Vendor

Product

Version

Microsoft

Windows 10 Version 1607

Affected: 10.0.14393.0 , < 10.0.14393.8868 (custom)

Microsoft	Windows 10 Version 1809	Affected: 10.0.17763.0 , < 10.0.17763.8389 (custom)
Microsoft	Windows 10 Version 21H2	Affected: 10.0.19044.0 , < 10.0.19044.6937 (custom)
Microsoft	Windows 10 Version 22H2	Affected: 10.0.19045.0 , < 10.0.19045.6937 (custom)
Microsoft	Windows 11 version 22H3	Affected: 10.0.22631.0 , < 10.0.22631.6649 (custom)
Microsoft	Windows 11 Version 23H2	Affected: 10.0.22631.0 , < 10.0.22631.6649 (custom)
Microsoft	Windows 11 Version 24H2	Affected: 10.0.26100.0 , < 10.0.26100.7840 (custom)
Microsoft	Windows 11 Version 25H2	Affected: 10.0.26200.0 , < 10.0.26200.7840 (custom)
Microsoft	Windows 11 version 26H1	Affected: 10.0.28000.0 , < 10.0.28000.1575 (custom)
Microsoft	Windows 11 Version 26H1	Affected: 10.0.28000.0 , < 10.0.28000.1575 (custom)
Microsoft	Windows Server 2016	Affected: 10.0.14393.0 , < 10.0.14393.8868 (custom)
Microsoft	Windows Server 2016 (Server Core installation)	Affected: 10.0.14393.0 , < 10.0.14393.8868 (custom)
Microsoft	Windows Server 2019	Affected: 10.0.17763.0 , < 10.0.17763.8389 (custom)
Microsoft	Windows Server 2019 (Server Core installation)	Affected: 10.0.17763.0 , < 10.0.17763.8389 (custom)
Microsoft	Windows Server 2022	Affected: 10.0.20348.0 , < 10.0.20348.4773 (custom)
Microsoft	Windows Server 2022, 23H2 Edition (Server Core installation)	Affected: 10.0.25398.0 , < 10.0.25398.2149 (custom)
Microsoft	Windows Server 2025	Affected: 10.0.26100.0 , < 10.0.26100.32370 (custom)
Microsoft	Windows Server 2025 (Server Core installation)	Affected: 10.0.26100.0 , < 10.0.26100.32370 (custom)

Date Public ?

2026-02-10 16:00

Show details on NVD website

JSON

To clipboard

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        {
          "name": "Windows Hyper-V Security Feature Bypass Vulnerability",
          "tags": [
            "vendor-advisory",
            "patch"
          ],
          "url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21255"
        }
      ],
      "title": "Windows Hyper-V Security Feature Bypass Vulnerability"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "f38d906d-7342-40ea-92c1-6c4a2c6478c8",
    "assignerShortName": "microsoft",
    "cveId": "CVE-2026-21255",
    "datePublished": "2026-02-10T17:51:38.926Z",
    "dateReserved": "2025-12-11T21:02:05.736Z",
    "dateUpdated": "2026-04-10T13:21:25.741Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

MSRC_CVE-2026-21255

CVE-2026-21255 (GCVE-0-2026-21255)

Tags

Sightings

Nomenclature