Windows Installer: Use-after-free leads to local privilege escalation
Summary
Windows Installer contains a use-after-free vulnerability (CWE-416) that allows an authorized attacker with local access to elevate privileges. Exploitation requires an existing local session, so the flaw is not directly reachable from the internet. Successful exploitation can give the attacker SYSTEM-level control of the affected machine.
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
- Windows 10 Version 22H2: before 10.0.19045.7846
- Windows 11 Version 23H2: before 10.0.22631.7711
- Windows 11 Version 24H2: before 10.0.26100.9974
- Windows 11 Version 25H2: 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
Unknown for the exact update packages. Fixed builds according to the CVE record are listed under affected. Install the November 2026 cumulative update for the respective Windows version.
Workaround
Unknown.
Exploitation
- No evidence of exploitation in the wild found.
- No public proof of concept found.
- Microsoft exploitability assessment not found. CISA SSVC: Exploitation none, Automatable no, Technical Impact total.
Our recommendation
- Install the November 2026 cumulative update on all Windows 10, 11 and Server systems, starting with shared and multi-user hosts.
- Verify the installed build against the Microsoft Security Update Guide.
- Keep users on standard (non-administrative) accounts until patched.
- Monitor for unexpected SYSTEM-level processes or installer activity.
Information from Microsoft (Patch Tuesday November 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)
- KB5131085, KB5131090, KB5131096, KB5131080, KB5131077, KB5132061
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- CVE Record CVE-2026-119929 (CVE Program) www.cve.org
- Microsoft Security Update Guide CVE-2026-119929 msrc.microsoft.com
- VulDB entry 434331 (CVSS discrepancy) vuldb.com
- Senserva KB 5131096 (update mapping, unconfirmed) senserva.com
- Tenable November 2026 Patch Tuesday review 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 11 Nov 2026, 03:40.
Original description (NVD)
Use after free 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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