CVE-2026-20810 - Vulnerability Details - OpenCVE

Free of memory not on the heap in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.

No CVSS v4.0

Attack Vector Local

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

Vendors	Products
Microsoft	Windows 10 1809 Windows 10 21h2 Windows 10 22h2 Windows Server 2019

No data.

No data.

No data.

References

Link	Providers
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20810

History

Tue, 13 Jan 2026 18:15:00 +0000

Type	Values Removed	Values Added
Description		Free of memory not on the heap in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.
Title		Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability
First Time appeared		Microsoft Microsoft windows 10 1809 Microsoft windows 10 21h2 Microsoft windows 10 22h2 Microsoft windows Server 2019
Weaknesses		CWE-590
CPEs		cpe:2.3:o:microsoft:windows_10_1809:::::::x86:* cpe:2.3:o:microsoft:windows_10_21H2:::::::x86:* cpe:2.3:o:microsoft:windows_10_22H2:::::::x64:* cpe:2.3:o:microsoft:windows_server_2019::::::::
Vendors & Products		Microsoft Microsoft windows 10 1809 Microsoft windows 10 21h2 Microsoft windows 10 22h2 Microsoft windows Server 2019
References		https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20810
Metrics		cvssV3_1 `{'score': 7.8, 'vector': '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'}`

MITRE

Status: PUBLISHED

Assigner: microsoft

Published: 2026-01-13T17:56:10.446Z

Updated: 2026-01-13T18:03:57.004Z

Reserved: 2025-12-03T05:54:20.372Z

Link: CVE-2026-20810

Vulnrichment

No data.

NVD

Status : Received

Published: 2026-01-13T18:16:07.547

Modified: 2026-01-13T18:16:07.547

Link: CVE-2026-20810

Redhat

No data.

OpenCVE Enrichment

No data.

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-20810", "assignerOrgId": "f38d906d-7342-40ea-92c1-6c4a2c6478c8", "state": "PUBLISHED", "assignerShortName": "microsoft", "dateReserved": "2025-12-03T05:54:20.372Z", "datePublished": "2026-01-13T17:56:10.446Z", "dateUpdated": "2026-01-13T18:03:57.004Z"}, "containers": {"cna": {"title": "Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability", "datePublic": "2026-01-13T08:00:00.000Z", "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x86:*", "versionStartIncluding": "10.0.17763.0", "versionEndExcluding": "10.0.17763.8276"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:*", "versionStartIncluding": "10.0.17763.0", "versionEndExcluding": "10.0.17763.8276"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:*", "versionStartIncluding": "10.0.17763.0", "versionEndExcluding": "10.0.17763.8276"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_10_21H2:*:*:*:*:*:*:x86:*", "versionStartIncluding": "10.0.19044.0", "versionEndExcluding": "10.0.19044.6809"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_10_22H2:*:*:*:*:*:*:x64:*", "versionStartIncluding": "10.0.19045.0", "versionEndExcluding": "10.0.19045.6809"}]}]}], "affected": [{"vendor": "Microsoft", "product": "Windows 10 Version 1809", "platforms": ["32-bit Systems", "x64-based Systems"], "versions": [{"version": "10.0.17763.0", "lessThan": "10.0.17763.8276", "versionType": "custom", "status": "affected"}]}, {"vendor": "Microsoft", "product": "Windows Server 2019", "platforms": ["x64-based Systems"], "versions": [{"version": "10.0.17763.0", "lessThan": "10.0.17763.8276", "versionType": "custom", "status": "affected"}]}, {"vendor": "Microsoft", "product": "Windows Server 2019 (Server Core installation)", "platforms": ["x64-based Systems"], "versions": [{"version": "10.0.17763.0", "lessThan": "10.0.17763.8276", "versionType": "custom", "status": "affected"}]}, {"vendor": "Microsoft", "product": "Windows 10 Version 21H2", "platforms": ["32-bit Systems", "ARM64-based Systems", "x64-based Systems"], "versions": [{"version": "10.0.19044.0", "lessThan": "10.0.19044.6809", "versionType": "custom", "status": "affected"}]}, {"vendor": "Microsoft", "product": "Windows 10 Version 22H2", "platforms": ["x64-based Systems", "ARM64-based Systems", "32-bit Systems"], "versions": [{"version": "10.0.19045.0", "lessThan": "10.0.19045.6809", "versionType": "custom", "status": "affected"}]}], "descriptions": [{"value": "Free of memory not on the heap in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.", "lang": "en-US"}], "problemTypes": [{"descriptions": [{"description": "CWE-590: Free of Memory not on the Heap", "lang": "en-US", "type": "CWE", "cweId": "CWE-590"}]}], "providerMetadata": {"orgId": "f38d906d-7342-40ea-92c1-6c4a2c6478c8", "shortName": "microsoft", "dateUpdated": "2026-01-13T18:03:57.004Z"}, "references": [{"name": "Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability", "tags": ["vendor-advisory", "patch"], "url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20810"}], "metrics": [{"format": "CVSS", "scenarios": [{"lang": "en-US", "value": "GENERAL"}], "cvssV3_1": {"version": "3.1", "baseSeverity": "HIGH", "baseScore": 7.8, "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"}}]}}}