TL;DR: Microsoft's October 13 updates fix CVE-2026-96951, a Windows Shell security feature bypass that Microsoft marks Exploited: Yes. CISA added it to KEV on 2026-10-13. (MSRC, KEV)
Critical / exploited fix
| Item | Detail | Source |
|---|---|---|
| CVE | CVE-2026-96951, Windows Shell Security Feature Bypass (CWE-77) | MSRC |
| Severity | Max severity Important; CVSS 3.1 8.8 / 8.2 | MSRC |
| Exploitation | Publicly disclosed: No. Exploited: Yes ("Exploitation Detected") | MSRC |
| What it bypasses | Mark of the Web (MOTW); delivered via a crafted file in an email or IM attack scenario, so the user has to take an action | MSRC |
| Affected / fixed | Windows 10, Windows 11 (23H2–26H2), and Server 2012 R2–2025. Example fixed builds: Win 11 24H2 10.0.26100.9711, 25H2 10.0.26200.9711, 26H2 10.0.26300.9711; Server 2025 10.0.26100.33650 | MSRC |
| Windows 11 KB | KB5127648 (OS Builds 26300.9711, 26200.9711, 26100.9711) | KB5127648 |
| KEV | dateAdded 2026-10-13, dueDate 2026-10-16, ransomware use Unknown | KEV |
Post-install impact
- Known issue (vendor-confirmed): Remote Desktop failures for non-admin users. See windows-11-rdp-0xc000000d-admin-protection.md.
- Behaviour change (documented, added Oct 15): KB5127648 changes the default for NTLMv1-derived SSO credentials from Audit to Enforce when
BlockNtlmv1SSOisn't set and Credential Guard is disabled. Microsoft says this "might affect Wi-Fi, Ethernet, and VPN connections that use MS-CHAPv2-based authentication." (KB5127648) - Press: BleepingComputer covered the black-screen fix and noted Microsoft confirmed the RDP issue. (BleepingComputer)
- Fixed by this update: the black-screen/desktop-loading issue (primarily AVD with FSLogix) and the AC-3 app crashes. (Release health)
Should you hold the patch?
MoonSec analysis: No. The update fixes an exploited bug and is due in KEV by Oct 16. Test RDP hosts (see the linked RDP entry) and MS-CHAPv2 Wi-Fi/VPN, in your first ring.
Last verified 2026-10-15Report an error: contact@moonsec.ai