CVE-2026-20871 — Desktop Windows Manager Elevation of Privilege Vulnerability

Executive Summary

Use after free in Desktop Windows Manager allows an authorized attacker to elevate privileges locally.

Overview

7.8

CVSS HIGH

Important

MS Severity

Not Exploited

MS Exploit Status

More Likely

MS Exploit Likelihood

Category Elevation of Privilege

Weakness CWE-416: Use After Free

Released Jan 13 2026

Last Updated Jan 13 2026

Publicly Disclosed No

CISA KEV Not Listed

Known Exploits None Known

EPSS Score 0.03989 — 0.89436 percentile

NVD CVSS 7.8 HIGH — matches MSRC

CVSS 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

ATTACK VECTOR

Local

ATTACK COMPLEXITY

Low

PRIVILEGES REQUIRED

Low

USER INTERACTION

None

SCOPE

Unchanged

CONFIDENTIALITY

High

INTEGRITY

High

AVAILABILITY

High

EXPLOIT CODE MATURITY

Unproven

REMEDIATION LEVEL

Official Fix

REPORT CONFIDENCE

Confirmed

Temporal Score: 6.8

EPSS Score

0.03989

probability of exploitation in the next 30 days

0.89436 percentile - updated 2026-07-25

View on FIRST.org

Affected Products

17 affected products

Product	KB Article	Severity	Impact	Restart Required
Windows 10 Version 21H2 for 32-bit Systems	`5073724 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 21H2 for ARM64-based Systems	`5073724 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 21H2 for x64-based Systems	`5073724 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 22H2 for 32-bit Systems	`5073724 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 22H2 for ARM64-based Systems	`5073724 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 22H2 for x64-based Systems	`5073724 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 11 Version 23H2 for ARM64-based Systems	`5073455 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 11 Version 23H2 for x64-based Systems	`5073455 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 11 Version 24H2 for ARM64-based Systems	`5074109 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 11 Version 24H2 for x64-based Systems	`5074109 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 11 Version 25H2 for ARM64-based Systems	`5074109 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 11 Version 25H2 for x64-based Systems	`5074109 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2022	`5073457 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2022 (Server Core installation)	`5073457 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2022, 23H2 Edition (Server Core installation)	`5073450 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2025	`5073379 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2025 (Server Core installation)	`5073379 (Security Update)`	Important	Elevation of Privilege	Yes

Patches

6 patches

Article	Type	Restart
`5073724`	Security Update	Yes
`5073455`	Security Update	Yes
`5074109`	Security Update	Yes
`5073457`	Security Update	Yes
`5073450`	Security Update	Yes
`5073379`	Security Update	Yes

Patch Diff

ghidriff · dwmcore.dll (KB5074109)

UAF in CSynchronousSuperWetInk destructor. Pre-patch, RemoveSource() was called only if IsSuperWetCompatible() returned true — a state that could be flipped by a low-priv attacker between registration and destruction (via CMD_SET_PROPERTY LookupMode=0), leaving a dangling pointer in CSuperWetInkManager::localStrokesVector. DirtyActiveInk later dereferences the freed vtable. Patch adds Feature_1732988217 CFR flag; when enabled, RemoveSource() runs unconditionally. Sibling fix in CDelegatedInkCanvas destructor uses the same flag. Full public exploit chain (GetRECT heap spray + __fnINSTRING/CStdAsyncStubBuffer2_Disconnect gadgets → VirtualProtect + WinExec) published by Joe Desimone / Elastic Security Labs.

Pre-patch version 10.0.26100.7309 Download

Post-patch version 10.0.26100.7623 Download

Function	Address	Change	Note
`CSynchronousSuperWetInk::~CSynchronousSuperWetInk`	`1802a9818 -> 1802a9ad8`	code, length, address, called	similarity 0.82
`wil::details::WilApi_GetFeatureEnabledState`	`18022b11c`	refcount, calling	similarity 1.0
`CDelegatedInkCanvas::~CDelegatedInkCanvas`	`18029b90c`	code, length, called	similarity 0.69
`wil::details::ReportUsageToService`	`1800ea660`	refcount, calling	similarity 0.96
`wil::details_abi::heap_buffer::push_back`	`180216760`	refcount, calling	similarity 1.0
wil::details::unique_storage<struct_wil::details::resource_policy<struct__RTL_SRWLOCK___ptr64,void_(__cdecl)(struct__RTL_SRWLOCK___ptr64),&void___cdecl_ReleaseSRWLockExclusive(struct__RTL_SRWLOCK___ptr64),struct_wistd::integral_constant<unsigned___int64,1>,struct__RTL_SRWLOCK___ptr64,struct__RTL_SRWLOCK___ptr64,0,std::nullptr_t>_>::~unique_storage<struct_wil::details::resource_policy<struct__RTL_SRWLOCK___ptr64,void_(__cdecl)(struct__RTL_SRWLOCK___ptr64),&void___cdecl_ReleaseSRWLockExclusive(struct__RTL_SRWLOCK___ptr64),struct_wistd::integral_constant<unsigned___int64,1>,struct__RTL_SRWLOCK___ptr64,struct__RTL_SRWLOCK___ptr64,0,std::nullptr_t>_>	`1802082fc`	refcount, calling	similarity 1.0
`wil::details::EnsureSubscribedToFeatureConfigurationChanges`	`180201d0c`	refcount, calling	similarity 1.0
`API-MS-WIN-CORE-SYNCH-L1-1-0.DLL::AcquireSRWLockExclusive`	`EXTERNAL:0000005d`	refcount, calling	similarity 1.0

View full diff report View RCA report Download PoC

Known Exploits

No known exploits have been linked for this CVE yet. When available, exploit references will be sourced from public repositories and may be unverified, incomplete, or non-functional. Always review code carefully before use in any environment.

Acknowledgments

Anonymous working with Trend Zero Day Initiative

References

MSRC Advisory MITRE NVD