CriticalCVE-2026-20805

Desktop Window Manager Information Disclosure Vulnerability (CVE-2026-20805)

Published 13.01.2026In CISA KEV since 13.01.2026Sources: pwn.watch, Msrc Update Guide, CVE.org

What is affected, what to do

Exposure of sensitive information to an unauthorized actor in Desktop Windows Manager allows an authorized attacker to disclose information locally.

The vulnerability is being actively exploited; treat it as a priority. Update Microsoft Windows 10 Version 1607 to version 10.0.14393.8783, Microsoft Windows 10 Version 1809 to version 10.0.17763.8276, Microsoft Windows 10 Version 21H2 to version 10.0.19044.6809. Immediate actions, mitigation and detection rules are in the runbook below.

Affected: Microsoft Windows 10 Version 1607 lt 10.0.14393.0..10.0.14393.8783
Microsoft Windows 10 Version 1809 lt 10.0.17763.0..10.0.17763.8276
Microsoft Windows 10 Version 21H2 lt 10.0.19044.0..10.0.19044.6809
Microsoft Windows 10 Version 22H2 lt 10.0.19045.0..10.0.19045.6809
Microsoft Windows 11 version 23H2 lt 10.0.22631.0..10.0.22631.6491
Microsoft Windows 11 Version 24H2 lt 10.0.26100.0..10.0.26100.7623
Microsoft Windows 11 Version 25H2 lt 10.0.26200.0..10.0.26200.7623
Microsoft Windows Server 2012 lt 6.2.9200.0..6.2.9200.25868
Microsoft Windows Server 2012 (Server Core installation) lt 6.2.9200.0..6.2.9200.25868
Microsoft Windows Server 2012 R2 lt 6.3.9600.0..6.3.9600.22968
Microsoft Windows Server 2012 R2 (Server Core installation) lt 6.3.9600.0..6.3.9600.22968
Microsoft Windows Server 2016 lt 10.0.14393.0..10.0.14393.8783
Microsoft Windows Server 2016 (Server Core installation) lt 10.0.14393.0..10.0.14393.8783
Microsoft Windows Server 2019 lt 10.0.17763.0..10.0.17763.8276
Microsoft Windows Server 2019 (Server Core installation) lt 10.0.17763.0..10.0.17763.8276
Microsoft Windows Server 2022 lt 10.0.20348.0..10.0.20348.4648
Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) lt 10.0.25398.0..10.0.25398.2092
Microsoft Windows Server 2025 lt 10.0.26100.0..10.0.26100.32230
Microsoft Windows Server 2025 (Server Core installation) lt 10.0.26100.0..10.0.26100.32230
Fixed in: Microsoft Windows 10 Version 1607 10.0.14393.8783
Microsoft Windows 10 Version 1809 10.0.17763.8276
Microsoft Windows 10 Version 21H2 10.0.19044.6809
Microsoft Windows 10 Version 22H2 10.0.19045.6809
Microsoft Windows 11 version 23H2 10.0.22631.6491
Microsoft Windows 11 Version 24H2 10.0.26100.7623
Microsoft Windows 11 Version 25H2 10.0.26200.7623
Microsoft Windows Server 2012 6.2.9200.25868
Microsoft Windows Server 2012 (Server Core installation) 6.2.9200.25868
Microsoft Windows Server 2012 R2 6.3.9600.22968
Microsoft Windows Server 2012 R2 (Server Core installation) 6.3.9600.22968
Microsoft Windows Server 2016 10.0.14393.8783
Microsoft Windows Server 2016 (Server Core installation) 10.0.14393.8783
Microsoft Windows Server 2019 10.0.17763.8276
Microsoft Windows Server 2019 (Server Core installation) 10.0.17763.8276
Microsoft Windows Server 2022 10.0.20348.4648
Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) 10.0.25398.2092
Microsoft Windows Server 2025 10.0.26100.32230
Microsoft Windows Server 2025 (Server Core installation) 10.0.26100.32230

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Metrics

5.5

Priority

XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

Source: NVD, CVSS v3

5.5

CVSS v3

Severity Medium on the scale from 0 to 10.

Source: pwn.watch, Msrc Update Guide, CVE.org

7.5 %

EPSS score

Moderate — model estimates 1-10% exploitation likelihood.

Source: FIRST EPSS, percentile 94.4

Show all metrics

Severity: Critical
Priority (0–325) The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first? Read in glossary: 212.33 Methodology
Exploit maturity An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack. Read in glossary: actively exploitedSource: VulnCheck KEV (opens in a new tab) How we classify
XIEM Effective CVSS XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command. Read in glossary: 5.5 Methodology
CVSS v3 CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions. Read in glossary: 5.5
EPSS score The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“. Read in glossary: 7.5 %; Moderate — model estimates 1-10% exploitation likelihood.
EPSS percentile The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking. Read in glossary: 94.4; Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
KEV status The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching. Read in glossary: Actively exploited
Published: 13.01.2026
In CISA KEV since The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching. Read in glossary: 13.01.2026
CWE CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect. Read in glossary: CWE-200

Response and mitigation

Why act now?

Prioritisation rationale

On its own this flaw is moderate. It is local-only, needs an authenticated low-privileged account, and affects confidentiality only. However, its KEV listing on release day shows it was already being used as a component of exploit chains before disclosure. Leaks like this typically expose memory addresses to defeat ASLR, so that a follow-on privilege escalation exploit runs reliably. Exploitation likelihood is notably higher than for most CVEs, while CISA reports no known ransomware use so far. Treat it as high priority for multi-user hosts, admin workstations and KRITIS-relevant systems, and as an accelerated (days, not weeks) patch for standard clients.

01
Runbook step 1
Immediate response (0-24 h)
- Deploy the January 2026 security updates: A patch is available from the vendor. Look up the KB number in the Microsoft Security Update Guide entry for CVE-2026-20805. Hosts must reach at least these builds:
  
  Win10 1607: 10.0.14393.8783
  
  Win10 1809: 10.0.17763.8276
  
  Win10 21H2/22H2: 10.0.19044.6809 / 10.0.19045.6809
  
  Win11 23H2: 10.0.22631.6491
  
  Win11 24H2/25H2: 10.0.26100.7623 / 10.0.26200.7623
  
  Server 2012: 6.2.9200.25868
- Patch shared, multi-user hosts first: This covers RDS session hosts, Citrix/VDI pools, jump hosts and shared admin workstations. Many low-privileged users there touch the same DWM instance, which makes a memory leak most valuable for follow-on privilege escalation.
- Check ESU coverage: Windows 10 22H2 and Server 2012 only receive this fix with an active Extended Security Updates licence. Track non-ESU systems as unpatched and isolate or decommission them.
- Verify the patch level, not just deployment:
  
  Defender for Endpoint: DeviceTvmSoftwareVulnerabilities | where CveId == "CVE-2026-20805"
  
  Alternatively, compare UBR under HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion against the target builds via Intune, SCCM or WMI.
- Don't cherry-pick: Ship the local privilege escalation (LPE) fixes from the same release alongside this one. DWM info leaks are typically used as an ASLR bypass chained with kernel or Win32k LPE, so partial rollouts leave the chain intact.
02
Runbook step 2
Mitigation layers
- Configuration: There is no official workaround. DWM is a core component and cannot be disabled. The vendor advisory gives no specific workaround guidance, so apply general hardening baselines.
- Application control: Use WDAC or AppLocker to block unsigned binaries from user-writable paths. These include %TEMP%, %APPDATA%, %LOCALAPPDATA%, C:\Users\Public and Downloads. Exploitation requires local code execution, so application control breaks the chain at step one.
- Endpoint hardening: Enforce these ASR rules in block mode:
  
  "Block executable files unless they meet prevalence, age or trusted list criteria"
  
  "Block Office applications from creating child processes"
  
  "Block process creations originating from PSExec and WMI commands"
  
  Also enable Credential Guard and LSA Protection (RunAsPPL) to limit the blast radius after a successful escalation.
- IAM/least privilege: Restrict interactive and RDP logon rights on servers via GPO ("Allow log on locally" and "Allow log on through Remote Desktop Services" limited to named groups only). Apply Deny log on locally to service and test accounts.
- Segmentation: Move unpatched legacy systems (especially Server 2012 without ESU) into a dedicated VLAN. Only permit RDP (TCP/UDP 3389) into it via PAM or a jump host. This shrinks the population of accounts that can obtain local access at all.
03
Runbook step 3
Detection rules
- Sysmon EID 10 (ProcessAccess):
  
  Trigger: TargetImage ends with \dwm.exe, SourceImage sits outside C:\Windows\System32\, and GrantedAccess includes read or duplicate rights (e.g. 0x1010, 0x1410, 0x1fffff).
  
  Sigma shape: selection: TargetImage|endswith: '\dwm.exe' / filter: SourceImage|startswith: 'C:\Windows\System32\'
- dwm.exe instability:
  
  Application log Event ID 1000/1001 (Application Error / WER) with dwm.exe as the faulting app.
  
  Repeated DWM restarts (new dwm.exe under Window Manager\DWM-*) outside patch reboots.
  
  KQL: DeviceProcessEvents | where FileName =~ "dwm.exe" | summarize count() by DeviceName, bin(Timestamp,1h) | where count_ > 3
- EDR process ancestry: An unsigned process launches from a user path. Shortly afterwards a System-integrity process appears, or a token switches to NT AUTHORITY\SYSTEM, with an ancestor that ran in user context.
  
  Sysmon EID 1, correlated on ParentProcessGuid and IntegrityLevel.
  
  Pattern: info leak, then LPE.
- Sysmon EID 8 (CreateRemoteThread) or EID 7 (ImageLoad) targeting dwm.exe with non-Microsoft-signed DLLs: Signed == false or Signature != "Microsoft Windows".
- Security log 4688/4672: Special-privilege logon (4672) for accounts that normally hold no admin rights, occurring shortly after a new binary executes on RDS, VDI or client hosts.

Detection rules

No NEOSEC detection rule is available for this vulnerability yet.

Classification under NIS2 and CRA

Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

NIS2 NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management. Read in glossary: Actively exploited: treat the vulnerability as a priority in vulnerability handling under Art. 21(2)(e) NIS2. If it is exploited in your environment, check the reporting obligation under Art. 23 (early warning within 24 hours).
CRA The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates. Read in glossary: Since 11.09.2026, manufacturers of affected products with digital elements must report actively exploited vulnerabilities under Art. 14 CRA, with an early warning within 24 hours via ENISA's single reporting platform.
ISO/IEC 27001 ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security. Read in glossary: Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

Description

Exposure of sensitive information to an unauthorized actor in Desktop Windows Manager allows an authorized attacker to disclose information locally.

Source: pwn.watch, Microsoft Security Update Guide, cvelistv5, CISA KEV Catalog, NVD (NIST), CVE.org (MITRE)

Affected products

The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

Affected products
		Affected versions	Fixed in
Microsoft	Windows 10 Version 1607	`10.0.14393.0 – < 10.0.14393.8783`	`10.0.14393.8783`
Microsoft	Windows 10 Version 1809	`10.0.17763.0 – < 10.0.17763.8276`	`10.0.17763.8276`
Microsoft	Windows 10 Version 21H2	`10.0.19044.0 – < 10.0.19044.6809`	`10.0.19044.6809`
Microsoft	Windows 10 Version 22H2	`10.0.19045.0 – < 10.0.19045.6809`	`10.0.19045.6809`
Microsoft	Windows 11 version 23H2	`10.0.22631.0 – < 10.0.22631.6491`	`10.0.22631.6491`
Microsoft	Windows 11 Version 24H2	`10.0.26100.0 – < 10.0.26100.7623`	`10.0.26100.7623`
Microsoft	Windows 11 Version 25H2	`10.0.26200.0 – < 10.0.26200.7623`	`10.0.26200.7623`
Microsoft	Windows Server 2012	`6.2.9200.0 – < 6.2.9200.25868`	`6.2.9200.25868`
Microsoft	Windows Server 2012 (Server Core installation)	`6.2.9200.0 – < 6.2.9200.25868`	`6.2.9200.25868`
Microsoft	Windows Server 2012 R2	`6.3.9600.0 – < 6.3.9600.22968`	`6.3.9600.22968`
Microsoft	Windows Server 2012 R2 (Server Core installation)	`6.3.9600.0 – < 6.3.9600.22968`	`6.3.9600.22968`
Microsoft	Windows Server 2016	`10.0.14393.0 – < 10.0.14393.8783`	`10.0.14393.8783`
Microsoft	Windows Server 2016 (Server Core installation)	`10.0.14393.0 – < 10.0.14393.8783`	`10.0.14393.8783`
Microsoft	Windows Server 2019	`10.0.17763.0 – < 10.0.17763.8276`	`10.0.17763.8276`
Microsoft	Windows Server 2019 (Server Core installation)	`10.0.17763.0 – < 10.0.17763.8276`	`10.0.17763.8276`
Microsoft	Windows Server 2022	`10.0.20348.0 – < 10.0.20348.4648`	`10.0.20348.4648`
Microsoft	Windows Server 2022, 23H2 Edition (Server Core installation)	`10.0.25398.0 – < 10.0.25398.2092`	`10.0.25398.2092`
Microsoft	Windows Server 2025	`10.0.26100.0 – < 10.0.26100.32230`	`10.0.26100.32230`
Microsoft	Windows Server 2025 (Server Core installation)	`10.0.26100.0 – < 10.0.26100.32230`	`10.0.26100.32230`

Vendors and products

Affected operating systems

Affected operating systems

Windows	microsoft	windows_10_1607	—
Windows	microsoft	windows_10_1809	—
Windows	microsoft	windows_10_21h2	—
Windows	microsoft	windows_10_22h2	—
Windows	microsoft	windows_11_23h2	—
Windows	microsoft	windows_11_24h2	—
Windows	microsoft	windows_11_25h2	—
Windows	microsoft	windows_server_2012	`r2`
Windows	microsoft	windows_server_2012	—
Windows	microsoft	windows_server_2016	—
Windows	microsoft	windows_server_2019	—
Windows	microsoft	windows_server_2022	—
Windows	microsoft	windows_server_2022_23h2	—
Windows	microsoft	windows_server_2025	—

Weakness classes (CWE)

CWE-200Exposure of Sensitive Information to an Unauthorized Actor
Class
The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.
Entry at MITRE CWE-200

Public exploit references

Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.

Public exploit references

CISA KEV Catalog	CISA Known Exploited Vulnerability (opens in a new tab)cisa.gov	actively exploited	13.01.2026
PoC-in-GitHub (nomi-sec)	CVE-2026-20805-PoC (opens in a new tab)github.com	PoC (publicly reported)reported, not verified	10.09.2026

References & sources

Microsoft Security Update GuideDesktop Window Manager Information Disclosure VulnerabilityVendor advisory, Patch
cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2026-20805government-resource
pwn.watchpwn.watch: Microsoft Windows: Microsoft Windows Information Disclosure Vulnerabilitypwn-watch
Microsoft Security Update GuideMicrosoft Windows — CVE-2026-20805pwn-watch
NVD (NIST)NVD: CVE-2026-20805pwn-watch
cisa.govCISA Known Exploited Vulnerabilities Catalogpwn-watch

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<a href="https://intel.neosec.eu/en/cve/CVE-2026-20805"><img src="https://intel.neosec.eu/badge/cve/CVE-2026-20805.svg?lang=en" alt="CVE-2026-20805 – NEOSEC Intel" height="20"></a>

What is affected, what to do

Metrics

Response and mitigation

Prioritisation rationale

Immediate response (0-24 h)

Mitigation layers

Detection rules

Detection rules

Classification under NIS2 and CRA

Description

Affected products

Vendors and products

Affected operating systems

Weakness classes (CWE)

Public exploit references

References & sources