CVE-2019-1040: Microsoft Windows 10

Medium severity, CVSS 5.3. EPSS: 48% chance of exploitation in the next 30 days.

A tampering vulnerability exists in Microsoft Windows when a man-in-the-middle attacker is able to successfully bypass the NTLM MIC (Message Integrity Check) protection. An attacker who successfully exploited this vulnerability could gain the ability to downgrade NTLM security features. To exploit this vulnerability, the attacker would need to tamper with the NTLM exchange. The attacker could then modify flags of the NTLM packet without invalidating the signature. The update addresses the vulnerability by hardening NTLM MIC protection on the server-side.

Affected products

• Microsoft Windows 10: affected versions not specified; version 1607 only; version 1703 only; version 1709 only; version 1803 only; version 1809 only; …
• Microsoft Windows 7: affected versions not specified
• Microsoft Windows 8.1: affected versions not specified
• Microsoft Windows Rt 8.1: affected versions not specified
• Microsoft Windows Server 2008: affected versions not specified; version r2 only
• Microsoft Windows Server 2012: affected versions not specified; version r2 only
• Microsoft Windows Server 2016: affected versions not specified; version 1803 only; version 1903 only
• Microsoft Windows Server 2019: affected versions not specified

Published 2019-06-12. Last modified 2026-06-17.