CVE-2019-1040 MEDIUM

CVE-2019-1040: Windows NTLM Tampering Vulnerability

Vendor Microsoft
Product Windows 10 Version 1703
Published June 12, 2019
Last update May 20, 2025

CVSS base score

5.3/10
Attack vector Network
Attack complexity High
Privileges required None
User interaction Required
Confidentiality None
Integrity High

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N/E:P/RL:O/RC:C

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

June 12, 2019 CVE published
May 20, 2025 Record updated