Windows Installer: Heap-based buffer overflow enables local privilege escalation
Summary
Windows Installer, the Windows component that installs, repairs and removes MSI packages, contains a heap-based buffer overflow. An authorized local user with a logged-on account can exploit it to gain elevated privileges, potentially up to SYSTEM. The flaw is not reachable from the internet by itself and needs no user interaction.
Affected
- Windows 10 Version 1607 (10.0.14393.0 to < 10.0.14393.9612)
- Windows 10 Version 1809 (10.0.17763.0 to < 10.0.17763.9376)
- Windows 10 Version 21H2 (10.0.19044.0 to < 10.0.19044.7807)
- Windows 10 Version 22H2 (10.0.19045.0 to < 10.0.19045.7807)
- Windows 11 Versions 23H2, 24H2, 25H2, 26H1 and 26H2 (see CNA record for build ranges)
- Windows Server 2012 and 2012 R2 (including Server Core)
- Windows Server 2016 (10.0.14393.0 to < 10.0.14393.9612)
Fixed in
- Windows 10 Version 1607: 10.0.14393.9612 (per CNA record, not yet verified against MSRC)
- Windows 10 Version 1809: 10.0.17763.9376 (per CNA record)
- Windows 10 Version 21H2: 10.0.19044.7807 (per CNA record)
- Windows 10 Version 22H2: 10.0.19045.7807 (per CNA record)
- Other products: see the MSRC Security Update Guide, as the aggregator data conflicts
- KB numbers: Unknown.
Workaround
Unknown.
Exploitation
- CISA SSVC: exploitation none, automatable no, technical impact total
- No evidence of exploitation in the wild found in the sources
- No public proof-of-concept code found
- EPSS 0.00341 (low predicted exploitation probability)
Our recommendation
- Patch Windows 10 Version 1607 endpoints and shared or terminal servers first, using the update listed in the MSRC advisory
- Check the MSRC advisory for the correct fixed build numbers before rollout, as the sources conflict
- Verify the end-of-support date of Windows 10 Version 1607 on Microsoft's lifecycle page and plan migration for unpatchable systems
- Limit local accounts, admin rights and interactive logons on affected hosts
- Monitor for msiexec or installer processes running with elevated rights
Information from Microsoft (Patch Tuesday October 2026)
- Severity (Microsoft)
- Important
- Impact
- Elevation of privilege – Windows Installer
- Status on Patch Tuesday
- Neither exploited nor publicly disclosed
- Exploitability assessment
- Exploitation less likely
- Product family
- Windows, Windows ESU (Extended Security Updates)
- Updates (KB)
- KB5126651, KB5126655, KB5126657, KB5126646, KB5127648, KB5126653
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-69471 msrc.microsoft.com
- CNA record mirror (Vulners CVE list) vulners.com
- NVD data via OpenCVE app.opencve.io
- Version table (Strix) www.strix.ai
- VulDB entry vuldb.com
- Rapid7 and EPSS mirror (Vulners NVD) vulners.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, 04:55.
Original description (NVD)
Heap-based buffer overflow in Windows Installer 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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