Windows Secondary Logon: Information disclosure via out-of-bounds read
Summary
A local out-of-bounds read in the Windows Secondary Logon service can disclose information. An authorized attacker with a valid low-privilege local account can read sensitive data from memory, but cannot change or disrupt the system. Remote exploitation is not indicated.
Affected
- Windows 10 Version 1607 (including Windows Server 2016, also Server Core)
- Windows 10 Version 1809 (including Windows Server 2019, also Server Core)
- Windows 10 Version 21H2
- Windows 10 Version 22H2
- Windows 11 Version 23H2
- Windows 11 Version 24H2
- Windows 11 Version 25H2
- Windows 11 Version 26H1
- Windows 11 Version 26H2
- Windows Server 2022
Fixed in
- Windows 10 1607 and Server 2016: 10.0.14393.9688 or later
- Windows 10 1809 and Server 2019: 10.0.17763.9487 or later
- Windows 10 21H2: 10.0.19044.7846 or later
- Windows 10 22H2: 10.0.19045.7846 or later
- Windows 11 23H2: 10.0.22631.7711 or later
- Windows 11 24H2 and 25H2: 10.0.26100.9974 or later (25H2 and 26H2 per vendor record)
- Windows 11 26H1: 10.0.28000.3501 or later
- Windows 11 26H2: 10.0.26300.9974 or later
- Windows Server 2022: 10.0.20348.5870 or later
Workaround
Unknown.
Exploitation
- Not known to be exploited in the wild.
- CISA SSVC: exploitation none, not automatable.
- No public proof of concept or exploit found at time of writing.
Our recommendation
- Install the November 2026 Windows security update on all affected systems.
- Verify the installed build on each device against the fixed versions above; Windows 10 systems on 1607, 1809, 21H2 or 22H2 depend on ESU or LTSC licensing.
- Prioritise multi-user systems, terminal servers and shared workstations.
- Limit local accounts and apply least privilege.
- Monitor for public exploit code and changes in exploitation status.
Information from Microsoft (Patch Tuesday November 2026)
- Severity (Microsoft)
- Important
- Impact
- Information disclosure – Secondary Logon
- Status on Patch Tuesday
- Neither exploited nor publicly disclosed
- Exploitability assessment
- Exploitation less likely
- Product family
- Windows, Windows ESU (Extended Security Updates)
- Updates (KB)
- KB5131291, KB5131085, KB5131096, KB5131090, KB5131087, KB5132061
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-96989 msrc.microsoft.com
- CVE Record CVE-2026-96989 www.cve.org
- CVE List V5 release cve_2026-11-11_0200Z github.com
- Rapid7 Patch Tuesday November 2026 (EM) www.rapid7.com
- Rapid7 EM Patch Tuesday November 2026 www.rapid7.com
- OffSeq Radar: CVE-2026-96989 radar.offseq.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, 16:17.
Original description (NVD)
Out-of-bounds read in Secondary Logon 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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