Microsoft Windows
CVE-2019-1338 — Windows NTLM Security Feature Bypass Vulnerability
Executive Summary
A security feature bypass vulnerability exists in Microsoft Windows when a man-in-the-middle attacker is able to successfully bypass the NTLMv2 protection if a client is also sending LMv2 responses. 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 be able to modify NTLM traffic exchange. The update addresses the vulnerability by hardening NTLMv2 protection on the server-side.
Overview
5.3
CVSS MEDIUM
Important
MS Severity
Not Exploited
MS Exploit Status
N/A
MS Exploit Likelihood
CVSS Vector
ATTACK VECTOR
Network
ATTACK COMPLEXITY
High
PRIVILEGES REQUIRED
None
USER INTERACTION
Required
SCOPE
Unchanged
Temporal Score: 4.8
EPSS Score
0.03319
probability of exploitation in the next 30 days
0.87003 percentile - updated 2026-06-20
View on FIRST.org
Affected Products
10 affected products
| Product | KB Article | Severity | Impact | Restart Required |
|---|---|---|---|---|
| Windows 7 for 32-bit Systems Service Pack 1 | 4519976 (Monthly Rollup) 4520003 (Security Only) |
Important | Security Feature Bypass | Yes |
| Windows 7 for x64-based Systems Service Pack 1 | 4519976 (Monthly Rollup) 4520003 (Security Only) |
Important | Security Feature Bypass | Yes |
| Windows Server 2008 for 32-bit Systems Service Pack 2 | 4520002 (Monthly Rollup) 4520009 (Security Only) |
Important | Security Feature Bypass | Yes |
| Windows Server 2008 for 32-bit Systems Service Pack 2 (Server Core installation) | 4520002 (Monthly Rollup) 4520009 (Security Only) |
Important | Security Feature Bypass | Yes |
| Windows Server 2008 for Itanium-Based Systems Service Pack 2 | 4520002 (Monthly Rollup) 4520009 (Security Only) |
Important | Security Feature Bypass | Yes |
| Windows Server 2008 for x64-based Systems Service Pack 2 | 4520002 (Monthly Rollup) 4520009 (Security Only) |
Important | Security Feature Bypass | Yes |
| Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation) | 4520002 (Monthly Rollup) 4520009 (Security Only) |
Important | Security Feature Bypass | Yes |
| Windows Server 2008 R2 for Itanium-Based Systems Service Pack 1 | 4519976 (Monthly Rollup) 4520003 (Security Only) |
Important | Security Feature Bypass | Yes |
| Windows Server 2008 R2 for x64-based Systems Service Pack 1 | 4519976 (Monthly Rollup) 4520003 (Security Only) |
Important | Security Feature Bypass | Yes |
| Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation) | 4519976 (Monthly Rollup) 4520003 (Security Only) |
Important | Security Feature Bypass | Yes |
Patches
2 patches
| Article | Type | Restart |
|---|---|---|
4519976 (Monthly Rollup) 4520003 |
Monthly Rollup | Yes |
4520002 (Monthly Rollup) 4520009 |
Monthly Rollup | Yes |
Known Exploits
No known exploits have been linked for this CVE yet. When available, exploit references will be sourced from public repositories and may be unverified, incomplete, or non-functional. Always review code carefully before use in any environment.
Acknowledgments
References
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