Vulnerability-Lookup

MSRC_CVE-2026-85921

Vulnerability from csaf_microsoft - Published: 2026-09-14 07:00 - Updated: 2026-09-27 07:00

Summary

Windows Secure Kernel Mode Elevation of Privilege Vulnerability

Severity

Critical

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-2026-85921

8.2 (High)


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

CWE-415 - Double Free

Affected products

Fixed 2 products

Product	Identifier	Version	Remediation
Windows 11 version 26H1 for x64-based Systems 10.0.28000.2956 Microsoft / Windows 11 version 26H1 for x64-based Systems		10.0.28000.2956
Windows 11 Version 26H1 for ARM64-based Systems 10.0.28000.2956 Microsoft / Windows 11 Version 26H1 for ARM64-based Systems		10.0.28000.2956

Known affected 2 products

Product	Identifier	Version	Remediation
Windows 11 Version 26H1 for ARM64-based Systems <10.0.28000.2956 Microsoft / Windows 11 Version 26H1 for ARM64-based Systems		<10.0.28000.2956	Vendor Fix fix
Windows 11 version 26H1 for x64-based Systems <10.0.28000.2956 Microsoft / Windows 11 version 26H1 for x64-based Systems		<10.0.28000.2956	Vendor Fix fix

Threats

Impact Elevation of Privilege

Exploit Status Publicly Disclosed:No;Exploited:No;Latest Software Release:Exploitation Less Likely

References

7 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

JSON

To clipboard

{
  "document": {
    "acknowledgments": [
      {
        "names": [
          "\u003ca href=\"https://x.com/vmpr0be\"\u003evmpr0be\u003c/a\u003e"
        ]
      }
    ],
    "aggregate_severity": {
      "namespace": "https://www.microsoft.com/en-us/msrc/security-update-severity-rating-system",
      "text": "Critical"
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    "category": "csaf_security_advisory",
    "csaf_version": "2.0",
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        "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"
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    "publisher": {
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      "contact_details": "secure@microsoft.com",
      "name": "Microsoft Security Response Center",
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        "summary": "CVE-2026-85921 Windows Secure Kernel Mode Elevation of Privilege Vulnerability - HTML",
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      },
      {
        "category": "self",
        "summary": "CVE-2026-85921 Windows Secure Kernel Mode Elevation of Privilege Vulnerability - CSAF",
        "url": "https://msrc.microsoft.com/csaf/advisories/2026/msrc_cve-2026-85921.json"
      },
      {
        "category": "external",
        "summary": "Microsoft Exploitability Index",
        "url": "https://www.microsoft.com/en-us/msrc/exploitability-index?rtc=1"
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          "title": "Assigning CNA"
        },
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          "category": "faq",
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        },
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          "category": "self",
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          "url": "https://msrc.microsoft.com/csaf/advisories/2026/msrc_cve-2026-85921.json"
        }
      ],
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          "date": "2026-09-14T07:00:00.000Z",
          "details": "10.0.28000.2956:Security Update:https://support.microsoft.com/help/5129194",
          "product_ids": [
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          ],
          "url": "https://support.microsoft.com/help/5129194"
        }
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      "scores": [
        {
          "cvss_v3": {
            "attackComplexity": "LOW",
            "attackVector": "LOCAL",
            "availabilityImpact": "HIGH",
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            "confidentialityImpact": "HIGH",
            "exploitCodeMaturity": "UNPROVEN",
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            "privilegesRequired": "HIGH",
            "remediationLevel": "OFFICIAL_FIX",
            "reportConfidence": "CONFIRMED",
            "scope": "CHANGED",
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        }
      ],
      "title": "Windows Secure Kernel Mode Elevation of Privilege Vulnerability"
    }
  ]
}

CVE-2026-85921 (GCVE-0-2026-85921)

Vulnerability from cvelistv5 – Published: 2026-09-14 17:19 – Updated: 2026-10-31 16:13

Title

Windows Secure Kernel Mode Elevation of Privilege Vulnerability

Summary

Double free in Windows Secure Kernel Mode allows an authorized attacker to elevate privileges locally.

Severity

8.2 (High)


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

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-14 00:00 UTC

CWE

CWE-415 - Double Free

Assigner

microsoft CNA under the mitre root

CNA scorecard B 82/100 over 3963 records in the last 180 days details

References

1 reference

URL	Tags
https://msrc.microsoft.com/update-guide/vulnerabi…	vendor-advisorypatch

Impacted products

1 product

Vendor	Product	Version
Microsoft	Windows 11 version 26H1	Affected: 10.0.28000.0 , < 10.0.28000.2956 (custom) cpe:2.3:o:microsoft:windows_11_26H1:::::::x64:*

Date Public

2026-09-14 14:00

Show details on NVD website

JSON

To clipboard

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                ],
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Sightings

Author	Source	Type	Date	Other

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.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

Order JSON

How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

Publication & reservation Sightings KEV catalogs Other timestamps

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

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