Windows Installer: Local privilege escalation through stack-based buffer overflow

Summary

A stack-based buffer overflow in the Windows Installer service allows a local user with low privileges to elevate their privileges. The attacker needs a local foothold first, for example a compromised standard user account or malware, and no user interaction is required. The CVSS 3.1 score is 7.0 (High).

Affected

• Windows 10 Version 1607 and Windows Server 2016: builds earlier than 10.0.14393.9612
• Windows 10 Version 1809 and Windows Server 2019: builds earlier than 10.0.17763.9376
• Windows 10 Version 21H2 and 22H2: builds earlier than 10.0.19045.7807
• Windows 11 Version 23H2: builds earlier than 10.0.22631.7652
• Windows 11 Version 24H2 and 25H2, Windows 11 26H2: builds earlier than 10.0.26100.9711 (24H2) and 10.0.26200.9711 (25H2), 10.0.26300.9711 (26H2)
• Windows 11 Version 26H1: builds earlier than 10.0.28000.3231
• Windows Server 2012 and 2012 R2: builds earlier than 6.2.9200.26434 and 6.3.9600.23470
• Server Core installations of the affected versions are also affected

Fixed in

• Windows 10 1607 and Windows Server 2016: 10.0.14393.9612 or later
• Windows 10 1809: 10.0.17763.9376 or later
• Windows 10 21H2 and 22H2: 10.0.19045.7807 or later
• Windows 11 23H2: 10.0.22631.7652 or later
• Windows 11 24H2 and 25H2: 10.0.26100.9711 and 10.0.26200.9711 or later
• Windows 11 26H1: 10.0.28000.3231 or later
• Windows 11 26H2: 10.0.26300.9711 or later
• Windows Server 2012 and 2012 R2: 6.2.9200.26434 and 6.3.9600.23470 or later
• KB number for Windows 10 1607: Unknown. Check the MSRC advisory.

Workaround

Unknown. No workaround is documented. Installing the security update is the fix.

Exploitation

• CISA KEV: not listed.
• CISA SSVC in the CVE record: exploitation none, automatable no, technical impact total.
• EPSS: below 1 percent.
• No public proof of concept was found in the research, but this does not prove none exists.
• No known in-the-wild exploitation was found.

Our recommendation

• Check which Windows versions and builds are in use, especially Windows 10 1607 and Server 2016.
• Install the October 2026 security update or the next cumulative update on affected systems; confirm the fixed build and KB in the MSRC advisory first.
• Prioritise computers with many local or shared user accounts.
• Check the Microsoft lifecycle status of Windows 10 1607 and plan an upgrade or isolation of any hosts still running it.
• Monitor for unusual local privilege changes or new administrative accounts.

Public exploits iAttack code is publicly available (PoC on GitHub, Metasploit or Exploit-DB).

PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.

Research sources

• Microsoft Security Update Guide: CVE-2026-83708 msrc.microsoft.com
• NVD record via Vulners vulners.com
• Microsoft CVE record via Vulners vulners.com
• OpenCVE entry app.opencve.io
• CVE List record via Vulners vulners.com
• Rapid7 record via Vulners 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 4 Nov 2026, 08:27.