Microsoft Windows Graphic Fonts: Remote code execution via heap-based overflow

Summary

The Graphic Fonts component of Microsoft Windows contains a heap-based buffer overflow (CWE-122). A remote attacker who gets a user to process a crafted font file can execute code, with the privileges of the current user. Microsoft rates the flaw CVSS 8.8, which assumes no privileges and required user interaction. Microsoft released fixes in the October 2026 Patch Tuesday.

Affected

• Windows 10 Version 1607 (10.0.14393.0 to before 10.0.14393.9612)
• Windows 10 Version 1809 (10.0.17763.0 to before 10.0.17763.9376)
• Windows 10 Version 21H2 (10.0.19044.0 to before 10.0.19044.7807)
• Windows 10 Version 22H2 (10.0.19045.0 to before 10.0.19045.7807)
• Windows 11 Version 23H2 (10.0.22631.0 to before 10.0.22631.7652)
• Windows 11 Version 24H2 (10.0.26100.0 to before 10.0.26100.9711)
• Windows 11 Version 25H2 (10.0.26200.0 to before 10.0.26200.9711)
• Windows 11 Version 26H1 (10.0.28000.0 to before 10.0.28000.3231)
• Windows 11 Version 26H2 (10.0.26300.0 to before 10.0.26300.9711)
• Windows Server 2012, including Server Core installation (6.2.9200.0 to before 6.2.9200.26434)
• Windows Server 2012 R2, including Server Core installation (6.3.9600.0 to before 6.3.9600.23470)
• Windows Server 2016 (10.0.14393.0 to before 10.0.14393.9612)

Fixed in

• Windows 10 Version 1607: build 10.0.14393.9612 or later (per CVE record; KB number unknown)
• Windows 10 Version 1809: build 10.0.17763.9376 or later
• 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: build 10.0.26100.9711 or later
• Windows 11 Version 25H2: build 10.0.26200.9711 or later
• Windows 11 Version 26H1: build 10.0.28000.3231 or later
• Windows 11 Version 26H2: build 10.0.26300.9711 or later
• Windows Server 2012: build 6.2.9200.26434 or later
• Windows Server 2012 R2: build 6.3.9600.23470 or later
• Windows Server 2016: build 10.0.14393.9612 or later

Workaround

Unknown. No vendor workaround was found.

Exploitation

• No evidence of exploitation in the wild found; not listed in CISA KEV.
• CISA SSVC: exploitation none, not automatable, total technical impact.
• Microsoft exploit maturity: unproven; vulnerability confirmed.
• No public proof of concept found.
• EPSS below 1% (very low).

Our recommendation

• Patch all listed Windows systems with the October 2026 security update, prioritising Windows 10 Version 1607 hosts.
• Verify the fixed build for each system via Microsoft's Security Update Guide, as the KB number for 1607 is not confirmed here.
• Check the support lifecycle of Windows 10 Version 1607 on Microsoft's website; if it is out of support, replace the system instead of only patching it.
• Until patched, restrict users from opening untrusted font files and filter font attachments at mail and web gateways.
• Monitor for exploitation indicators and review the exposure of unpatched hosts.

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-2026-69326 msrc.microsoft.com
• OpenCVE: CVE-2026-69326 app.opencve.io
• VulDB: CVE-2026-69326 vuldb.com
• Vulners NVD mirror: CVE-2026-69326 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 31 Oct 2026, 19:06.