Microsoft Windows: Elevation of privilege via integer overflow in HID Parser Library

Summary

A integer overflow or wraparound in the HID Parser Library of Microsoft Windows allows a locally authorized attacker to elevate privileges. The attacker needs local access and a low-privilege account, so this flaw is a privilege escalation step rather than an initial access vector. CVSS 7.8 (High) and CISA SSVC rates technical impact as total.

Affected

• Windows 10 Version 1809 and Windows Server 2019 (including Server Core): builds 10.0.17763.0 to below 10.0.17763.9376
• Windows 10 Version 21H2: builds 10.0.19044.0 to below 10.0.19044.7807
• Windows 10 Version 22H2: builds 10.0.19045.0 to below 10.0.19045.7807
• Windows 11 Version 23H2: builds 10.0.22631.0 to below 10.0.22631.7652
• Windows 11 Version 24H2 and 25H2, Windows 11 Version 26H2: builds below 10.0.26100.9711, 10.0.26200.9711 and 10.0.26300.9711 respectively
• Windows 11 Version 26H1: builds 10.0.28000.0 to below 10.0.28000.3231
• Windows Server 2022: builds 10.0.20348.0 to below 10.0.20348.5761
• Windows Server 2025 (including Server Core): builds 10.0.26100.0 to below 10.0.26100.33650

Fixed in

• Windows 10 Version 1809 and Windows Server 2019: build 10.0.17763.9376 or later (Microsoft Security Update Guide, October 2026 Patch Tuesday)
• Windows 10 Version 21H2: build 10.0.19044.7807 or later
• Windows 10 Version 22H2: build 10.0.19045.7807 or later
• Windows 11 Version 23H2: build 10.0.22631.7652 or later
• Windows 11 Version 24H2 / 25H2 / 26H2: build 10.0.26100.9711 / 10.0.26200.9711 / 10.0.26300.9711 or later
• Windows 11 Version 26H1: build 10.0.28000.3231 or later
• Windows Server 2022: build 10.0.20348.5761 or later
• Windows Server 2025: build 10.0.26100.33650 or later

Workaround

Unknown.

Exploitation

• Not listed in CISA KEV.
• CISA SSVC: exploitation none, automatable no, technical impact total.
• EPSS about 0.4%.
• No public proof-of-concept known.

Our recommendation

• Patch Windows 10 1809 and Windows Server 2019 hosts to build 10.0.17763.9376 or later in the October 2026 update cycle, and check all other affected Windows versions in the same way.
• Treat multi-user systems, Remote Desktop and terminal servers as high priority; treat single-user workstations as standard priority.
• Check whether Windows 10 1809 is still supported on your machines; if not, plan an upgrade instead.
• Verify the exact fixed build in the MSRC table before rollout, because the NVD status and some third-party version data were not fully confirmed.
• Monitor for unexpected privilege changes and new administrator accounts on local systems.

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-2026-83877 msrc.microsoft.com
• OpenCVE: CVE-2026-83877 (CISA SSVC, KEV data) app.opencve.io
• Vulners: CVE-2026-83877 CVE list record (CNA version data) vulners.com
• Vulners: CVE-2026-83877 NVD record (EPSS) 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, 02:41.