Windows: Local privilege escalation via out-of-bounds read in partition driver
Summary
The Windows Partition Management Driver contains an out-of-bounds read (CWE-125) that allows an authorized local attacker to elevate privileges. The CVSS base score is 7.8 (High), and the CISA SSVC assessment rates the technical impact as total. Exploitation requires local access with low privileges and no user interaction, so the risk comes from compromised standard accounts or malicious local users, not from the internet.
Affected
- Windows 10 Version 1607 and Windows Server 2016: 10.0.14393.0 before 10.0.14393.9612
- Windows 10 Version 1809: 10.0.17763.0 before 10.0.17763.9376
- Windows 10 Version 21H2: 10.0.19044.0 before 10.0.19044.7807
- Windows 10 Version 22H2: 10.0.19045.0 before 10.0.19045.7807
- Windows 11 Version 23H2: 10.0.22631.0 before 10.0.22631.7652
- Windows 11 Version 24H2: 10.0.26100.0 before 10.0.26100.9711
- Windows 11 Version 25H2: 10.0.26200.0 before 10.0.26200.9711
- Windows 11 Version 26H1: 10.0.28000.0 before 10.0.28000.3231
- Windows 11 Version 26H2: 10.0.26300.0 before 10.0.26300.9711
- Windows Server 2012 (including Server Core): 6.2.9200.0 before 6.2.9200.26434
- Windows Server 2012 R2 (including Server Core): 6.3.9600.0 before 6.3.9600.23470
Fixed in
- Windows 10 Version 1607 and Windows Server 2016: 10.0.14393.9612
- Windows 10 Version 1809: 10.0.17763.9376
- Windows 10 Version 21H2 and 22H2: 10.0.19044.7807 and 10.0.19045.7807
- Windows 11 Version 23H2: 10.0.22631.7652
- Windows 11 Version 24H2 and 25H2: 10.0.26100.9711 and 10.0.26200.9711
- Windows 11 Version 26H1: 10.0.28000.3231
- Windows 11 Version 26H2: 10.0.26300.9711
- Windows Server 2012: 6.2.9200.26434
- Windows Server 2012 R2: 6.3.9600.23470
KB numbers: Unknown. Check the MSRC page for the package per build.
Workaround
Unknown. No vendor workaround or mitigation is known; the security update is the only remedy.
Exploitation
- No evidence of exploitation in the wild was found.
- CISA SSVC: exploitation none, automatable no, technical impact total.
- EPSS is about 0.3%.
- Exploit code maturity in the CVSS temporal vector is unproven (E:U).
Our recommendation
- Inventory all Windows hosts, not only Windows 10 1607, and identify affected builds, including Windows Server 2016 and 2012 systems.
- Install the October 2026 security update for each affected build as listed on the MSRC page.
- Replace or isolate Windows 10 1607 systems that cannot be patched, and restrict local logon. Verify the support status of this edition on Microsoft's lifecycle page.
- Monitor for public exploit code and check the MSRC page for updates.
Information from Microsoft (Patch Tuesday October 2026)
- Severity (Microsoft)
- Important
- Impact
- Elevation of privilege – Windows Partition Management Driver
- Status on Patch Tuesday
- Neither exploited nor publicly disclosed
- Exploitability assessment
- Exploitation unlikely
- Product family
- Windows, Windows ESU (Extended Security Updates)
- Updates (KB)
- KB5126835, KB5126836, KB5126868, KB5126651, KB5126657, KB5126655
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-103553 msrc.microsoft.com
- NVD via Vulners: CVE-2026-103553 vulners.com
- CVE record mirror: CVE-2026-103553 cve.threatint.com
- Strix CVE record: CVE-2026-103553 www.strix.ai
- Tenable plugin 365473 www.tenable.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 2 Nov 2026, 05:07.
Original description (NVD)
Out-of-bounds read in Windows Partition Management Driver allows an authorized attacker to elevate privileges 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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