Windows Smart Card: Use-after-free allows local privilege escalation

Summary

Microsoft Windows with the Smart Card component contains a use-after-free flaw (CWE-416) that Microsoft lists as an elevation of privilege vulnerability. An attacker with a valid low-privilege local account can exploit it to gain higher privileges, which Microsoft and NVD rate as high impact to confidentiality, integrity and availability (CVSS 3.1 base score 7.0). Remote exploitation is not possible, and exploitation requires local logon access and a high attack complexity.

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 and 2012 (Server Core): 6.2.9200.0 to before 6.2.9200.26434
• Windows Server 2012 R2 and 2012 R2 (Server Core): 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

• Security update of October 13, 2026 (Patch Tuesday) for the affected builds listed above
• Exact knowledge base article numbers: check the MSRC page directly. Unknown.

Workaround

Unknown. No workaround is documented beyond applying the patch.

Exploitation

• Microsoft rates exploit code maturity as Unproven.
• Not listed in the CISA Known Exploited Vulnerabilities catalog.
• EPSS score below 1 percent (very low).
• No public proof-of-concept exploit found in our searches; this does not rule one out.
• CISA SSVC: exploitation none, automatable no, technical impact total.
• Exploitation in the wild: unknown.

Our recommendation

• Deploy the October 2026 security update to all affected systems and restart them afterwards.
• Verify the installed build number after patching.
• Prioritise Windows 10 Version 1607 and Windows Server 2016 systems, or upgrade them, as they are older and more likely to be unsupported.
• Focus on shared workstations, terminal servers and machines used by contractors or untrusted users with local logons.
• Monitor for unusual privilege changes or new local administrator 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-2026-83584 msrc.microsoft.com
• Microsoft Security Update Guide (en-US): CVE-2026-83584 msrc.microsoft.com
• NVD record via Vulners: CVE-2026-83584 vulners.com
• OpenCVE: CVE-2026-83584 app.opencve.io
• Strix: CVE-2026-83584 www.strix.ai

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, 08:41.