Microsoft Windows Win32k: Information disclosure vulnerability
Summary
The Win32k kernel-mode driver in Windows, which handles graphical and window functions, can expose sensitive system information to an unauthorized control sphere (CWE-497). A local attacker with low privileges and no user interaction can read this information. The impact is limited to confidentiality (CVSS 5.5, Medium). The flaw is not reachable from the internet, but it is a risk on shared or multi-user systems where an attacker already has a foothold.
Affected
- Windows 10 Version 1607 and Windows Server 2016 (including Server Core): before 10.0.14393.9688
- Windows 10 Version 1809 and Windows Server 2019 (including Server Core): before 10.0.17763.9487
- Windows 10 Version 21H2: before 10.0.19044.7846 (unverified)
- Windows 10 Version 22H2: before 10.0.19045.7846 (unverified)
- Windows 11 Version 23H2: before 10.0.22631.7711
- Windows 11 Version 24H2: before 10.0.26100.9974
- Windows 11 Version 25H2 and build branch 10.0.26200: before 10.0.26200.9974
- Windows 11 Version 26H1: before 10.0.28000.3501
- Windows 11 Version 26H2: before 10.0.26300.9974
- Windows Server 2022: before 10.0.20348.5870
Fixed in
- Install the November 2026 cumulative update for the affected release (builds listed above as fixed in the CNA record).
- Exact KB numbers: Unknown. Check the MSRC advisory.
Workaround
Unknown. No vendor workaround identified.
Exploitation
- Not known to be exploited in the wild.
- CISA SSVC: exploitation none, not automatable, partial technical impact.
- Rapid7 rates exploitation as less likely. No public proof of concept found.
Our recommendation
- Install the November 2026 security update on all affected Windows systems and servers.
- Prioritise terminal servers, systems with multiple local users and any systems still on ESU or older builds (1607, 1809, 21H2).
- Confirm the fixed build and KB numbers in the MSRC advisory before rollout.
- Restrict local logon to trusted accounts and monitor for suspicious local activity.
Information from Microsoft (Patch Tuesday November 2026)
- Severity (Microsoft)
- Important
- Impact
- Information disclosure – Windows Win32K
- Status on Patch Tuesday
- Neither exploited nor publicly disclosed
- Exploitability assessment
- Exploitation less likely
- Product family
- Windows, Windows ESU (Extended Security Updates), Microsoft Office
- Updates (KB)
- KB5131291, KB5131085, KB5131096, KB5131090, KB5131087, KB5132061
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- CVE.org record CVE-2026-119856 www.cve.org
- Microsoft Security Update Guide CVE-2026-119856 msrc.microsoft.com
- Rapid7 Patch Tuesday November 2026 www.rapid7.com
- BleepingComputer: Microsoft November 2026 Patch Tuesday www.bleepingcomputer.com
- Strix AI CVE-2026-119856 www.strix.ai
- Senserva KB5132061 senserva.com
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 11 Nov 2026, 16:43.
Original description (NVD)
Exposure of sensitive system information to an unauthorized control sphere in Windows Win32K allows an authorized attacker to disclose information locally.
NVD references (1)
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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