MSRC_CVE-2026-66804
Vulnerability from csaf_microsoft - Published: 2026-08-11 07:00 - Updated: 2026-08-14 07:00Summary
Microsoft Windows Cross Device Service Elevation of Privilege 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.
CWE-284
- Improper Access Control
Affected products
Fixed
9 products
| Product | Identifier | Version | Remediation |
|---|---|---|---|
|
Windows 10 Version 22H2 for x64-based Systems 10.0.19045.7663
Windows 10 Version 22H2 for x64-based Systems
|
10.0.19045.7663 | ||
|
Windows 10 Version 22H2 for ARM64-based Systems 10.0.19045.7663
Windows 10 Version 22H2 for ARM64-based Systems
|
10.0.19045.7663 | ||
|
Windows 10 Version 22H2 for 32-bit Systems 10.0.19045.7663
Windows 10 Version 22H2 for 32-bit Systems
|
10.0.19045.7663 | ||
|
Windows 11 Version 24H2 for ARM64-based Systems 10.0.26200.9106
Windows 11 Version 24H2 for ARM64-based Systems
|
10.0.26200.9106 | ||
|
Windows 11 Version 24H2 for x64-based Systems 10.0.26100.9168
Windows 11 Version 24H2 for x64-based Systems
|
10.0.26100.9168 | ||
|
Windows 11 Version 25H2 for ARM64-based Systems 10.0.26200.9168
Windows 11 Version 25H2 for ARM64-based Systems
|
10.0.26200.9168 | ||
|
Windows 11 Version 25H2 for x64-based Systems 10.0.26200.9168
Windows 11 Version 25H2 for x64-based Systems
|
10.0.26200.9168 | ||
|
Windows 11 version 26H1 for x64-based Systems 10.0.28000.2704
Windows 11 version 26H1 for x64-based Systems
|
10.0.28000.2704 | ||
|
Windows 11 Version 26H1 for ARM64-based Systems 10.0.28000.2704
Windows 11 Version 26H1 for ARM64-based Systems
|
10.0.28000.2704 |
Known affected
9 products
| Product | Identifier | Version | Remediation |
|---|---|---|---|
|
Windows 11 Version 26H1 for ARM64-based Systems <10.0.28000.2704
Windows 11 Version 26H1 for ARM64-based Systems
|
<10.0.28000.2704 |
Vendor Fix
fix
|
|
|
Windows 11 version 26H1 for x64-based Systems <10.0.28000.2704
Windows 11 version 26H1 for x64-based Systems
|
<10.0.28000.2704 |
Vendor Fix
fix
|
|
|
Windows 11 Version 25H2 for x64-based Systems <10.0.26200.9168
Windows 11 Version 25H2 for x64-based Systems
|
<10.0.26200.9168 |
Vendor Fix
fix
Vendor Fix
fix
|
|
|
Windows 11 Version 25H2 for ARM64-based Systems <10.0.26200.9168
Windows 11 Version 25H2 for ARM64-based Systems
|
<10.0.26200.9168 |
Vendor Fix
fix
Vendor Fix
fix
|
|
|
Windows 11 Version 24H2 for x64-based Systems <10.0.26100.9168
Windows 11 Version 24H2 for x64-based Systems
|
<10.0.26100.9168 |
Vendor Fix
fix
Vendor Fix
fix
|
|
|
Windows 11 Version 24H2 for ARM64-based Systems <10.0.26200.9106
Windows 11 Version 24H2 for ARM64-based Systems
|
<10.0.26200.9106 |
Vendor Fix
fix
Vendor Fix
fix
|
|
|
Windows 10 Version 22H2 for 32-bit Systems <10.0.19045.7663
Windows 10 Version 22H2 for 32-bit Systems
|
<10.0.19045.7663 |
Vendor Fix
fix
|
|
|
Windows 10 Version 22H2 for ARM64-based Systems <10.0.19045.7663
Windows 10 Version 22H2 for ARM64-based Systems
|
<10.0.19045.7663 |
Vendor Fix
fix
|
|
|
Windows 10 Version 22H2 for x64-based Systems <10.0.19045.7663
Windows 10 Version 22H2 for x64-based Systems
|
<10.0.19045.7663 |
Vendor Fix
fix
|
Threats
Impact
Elevation of Privilege
Exploit Status
Publicly Disclosed:No;Exploited:No;Latest Software Release:Exploitation More Likely
References
7 references
{
"document": {
"acknowledgments": [
{
"names": [
"James Forshaw with Google Project Zero"
]
},
{
"names": [
"shoodagiri with \u003ca href=\"https://gmo-cybersecurity.com/\"\u003eGMO Cybersecurity by Ierae Inc\u003c/a\u003e"
]
},
{
"names": [
"\u003ca href=\"https://www.linkedin.com/in/daniele-linguaglossa/\"\u003eDaniele Linguaglossa\u003c/a\u003e"
]
},
{
"names": [
"\u003ca href=\"https://infosec.exchange/@wdormann\"\u003eWill Dormann\u003c/a\u003e with \u003ca href=\"https://vu.ls/\"\u003eVul Labs\u003c/a\u003e"
]
},
{
"names": [
"yhw \u0026amp; txz"
]
},
{
"names": [
"\u003ca href=\"https://twitter.com/philiptsukerman\"\u003ePhilip Tsukerman\u003c/a\u003e with Palo Alto Networks"
]
},
{
"names": [
"Anonymous"
]
},
{
"names": [
"\u003ca href=\"https://github.com/rat5ak\"\u003eDaniel Wade\u003c/a\u003e with \u003ca href=\"https://nadsec.online/\"\u003enadsec\u003c/a\u003e"
]
},
{
"names": [
"\u003ca href=\"https://www.linkedin.com/in/david-c-826599a4/\"\u003eDavid Carliez\u003c/a\u003e with DC CyberSecurity"
]
},
{
"names": [
"\u003ca href=\"https://x.com/thomasklemenc\"\u003eThomas Klemenc\u003c/a\u003e"
]
},
{
"names": [
"sorte"
]
},
{
"names": [
"haowei yan"
]
}
],
"aggregate_severity": {
"namespace": "https://www.microsoft.com/en-us/msrc/security-update-severity-rating-system",
"text": "Important"
},
"category": "csaf_security_advisory",
"csaf_version": "2.0",
"distribution": {
"text": "Public",
"tlp": {
"label": "WHITE",
"url": "https://www.first.org/tlp/"
}
},
"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-2026-66804 Microsoft Windows Cross Device Service Elevation of Privilege Vulnerability - HTML",
"url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66804"
},
{
"category": "self",
"summary": "CVE-2026-66804 Microsoft Windows Cross Device Service Elevation of Privilege Vulnerability - CSAF",
"url": "https://msrc.microsoft.com/csaf/advisories/2026/msrc_cve-2026-66804.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": "Microsoft Windows Cross Device Service Elevation of Privilege Vulnerability",
"tracking": {
"current_release_date": "2026-08-14T07:00:00.000Z",
"generator": {
"date": "2026-08-14T16:40:07.777Z",
"engine": {
"name": "MSRC Generator",
"version": "1.0"
}
},
"id": "msrc_CVE-2026-66804",
"initial_release_date": "2026-08-11T07:00:00.000Z",
"revision_history": [
{
"date": "2026-08-11T07:00:00.000Z",
"legacy_version": "1",
"number": "1",
"summary": "Information published."
},
{
"date": "2026-08-12T07:00:00.000Z",
"legacy_version": "1.1",
"number": "2",
"summary": "Updated an acknowledgement. This is an informational change only."
},
{
"date": "2026-08-13T07:00:00.000Z",
"legacy_version": "1.2",
"number": "3",
"summary": "Acknowledgement Updated"
},
{
"date": "2026-08-14T07:00:00.000Z",
"legacy_version": "1.3",
"number": "4",
"summary": "Acknowledgement Updated"
}
],
"status": "final",
"version": "4"
}
},
"product_tree": {
"branches": [
{
"branches": [
{
"category": "product_version_range",
"name": "\u003c10.0.19045.7663",
"product": {
"name": "Windows 10 Version 22H2 for x64-based Systems \u003c10.0.19045.7663",
"product_id": "9"
}
},
{
"category": "product_version",
"name": "10.0.19045.7663",
"product": {
"name": "Windows 10 Version 22H2 for x64-based Systems 10.0.19045.7663",
"product_id": "12097"
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],
"category": "product_name",
"name": "Windows 10 Version 22H2 for x64-based Systems"
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{
"branches": [
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"name": "\u003c10.0.19045.7663",
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"product_id": "8"
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{
"category": "product_version",
"name": "10.0.19045.7663",
"product": {
"name": "Windows 10 Version 22H2 for ARM64-based Systems 10.0.19045.7663",
"product_id": "12098"
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"category": "product_name",
"name": "Windows 10 Version 22H2 for ARM64-based Systems"
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"branches": [
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"category": "product_version_range",
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"product_id": "7"
}
},
{
"category": "product_version",
"name": "10.0.19045.7663",
"product": {
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],
"category": "product_name",
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{
"branches": [
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"category": "product_version_range",
"name": "\u003c10.0.26200.9168",
"product": {
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"product_id": "4"
}
},
{
"category": "product_version",
"name": "10.0.26200.9168",
"product": {
"name": "Windows 11 Version 25H2 for ARM64-based Systems 10.0.26200.9168",
"product_id": "20437"
}
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],
"category": "product_name",
"name": "Windows 11 Version 25H2 for ARM64-based Systems"
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"branches": [
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"category": "product_version_range",
"name": "\u003c10.0.26200.9168",
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"product_id": "3"
}
},
{
"category": "product_version",
"name": "10.0.26200.9168",
"product": {
"name": "Windows 11 Version 25H2 for x64-based Systems 10.0.26200.9168",
"product_id": "20438"
}
}
],
"category": "product_name",
"name": "Windows 11 Version 25H2 for x64-based Systems"
},
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"branches": [
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"category": "product_version_range",
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"product_id": "6"
}
},
{
"category": "product_version",
"name": "10.0.26200.9106",
"product": {
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"name": "10.0.28000.2704",
"product": {
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"category": "product_name",
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"product_id": "1"
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{
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"name": "10.0.28000.2704",
"product": {
"name": "Windows 11 Version 26H1 for ARM64-based Systems 10.0.28000.2704",
"product_id": "20854"
}
}
],
"category": "product_name",
"name": "Windows 11 Version 26H1 for ARM64-based Systems"
}
]
},
"vulnerabilities": [
{
"cve": "CVE-2026-66804",
"cwe": {
"id": "CWE-284",
"name": "Improper Access Control"
},
"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?"
}
],
"product_status": {
"fixed": [
"12097",
"12098",
"12099",
"12389",
"12390",
"20437",
"20438",
"20853",
"20854"
],
"known_affected": [
"1",
"2",
"3",
"4",
"5",
"6",
"7",
"8",
"9"
]
},
"references": [
{
"category": "self",
"summary": "CVE-2026-66804 Microsoft Windows Cross Device Service Elevation of Privilege Vulnerability - HTML",
"url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66804"
},
{
"category": "self",
"summary": "CVE-2026-66804 Microsoft Windows Cross Device Service Elevation of Privilege Vulnerability - CSAF",
"url": "https://msrc.microsoft.com/csaf/advisories/2026/msrc_cve-2026-66804.json"
}
],
"remediations": [
{
"category": "vendor_fix",
"date": "2026-08-11T07:00:00.000Z",
"details": "10.0.19045.7663:Security Update:https://support.microsoft.com/help/5120249",
"product_ids": [
"9",
"8",
"7"
],
"url": "https://support.microsoft.com/help/5120249"
},
{
"category": "vendor_fix",
"date": "2026-08-11T07:00:00.000Z",
"details": "10.0.26200.9168:Security Update:https://support.microsoft.com/help/5121003",
"product_ids": [
"4",
"3"
],
"url": "https://support.microsoft.com/help/5121003"
},
{
"category": "vendor_fix",
"date": "2026-08-11T07:00:00.000Z",
"details": "10.0.26200.9106:Security Hotpatch Update:https://support.microsoft.com/help/5120994",
"product_ids": [
"4",
"3",
"6"
],
"url": "https://support.microsoft.com/help/5120994"
},
{
"category": "vendor_fix",
"date": "2026-08-11T07:00:00.000Z",
"details": "10.0.26100.9168:Security Update:https://support.microsoft.com/help/5121003",
"product_ids": [
"6",
"5"
],
"url": "https://support.microsoft.com/help/5121003"
},
{
"category": "vendor_fix",
"date": "2026-08-11T07:00:00.000Z",
"details": "10.0.26100.9106:Security Hotpatch Update:https://support.microsoft.com/help/5120994",
"product_ids": [
"5"
],
"url": "https://support.microsoft.com/help/5120994"
},
{
"category": "vendor_fix",
"date": "2026-08-11T07:00:00.000Z",
"details": "10.0.28000.2704:Security Update:https://support.microsoft.com/help/5121000",
"product_ids": [
"2",
"1"
],
"url": "https://support.microsoft.com/help/5121000"
}
],
"scores": [
{
"cvss_v3": {
"attackComplexity": "LOW",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 7.8,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"environmentalScore": 0.0,
"exploitCodeMaturity": "UNPROVEN",
"integrityImpact": "HIGH",
"privilegesRequired": "LOW",
"remediationLevel": "OFFICIAL_FIX",
"reportConfidence": "CONFIRMED",
"scope": "UNCHANGED",
"temporalScore": 6.8,
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C",
"version": "3.1"
},
"products": [
"1",
"2",
"3",
"4",
"5",
"6",
"7",
"8",
"9"
]
}
],
"threats": [
{
"category": "impact",
"details": "Elevation of Privilege"
},
{
"category": "exploit_status",
"details": "Publicly Disclosed:No;Exploited:No;Latest Software Release:Exploitation More Likely"
}
],
"title": "Microsoft Windows Cross Device Service Elevation of Privilege Vulnerability"
}
]
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
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.
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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.
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.
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