STIGQter: STIG Summary: Microsoft Windows 11 Security Technical Implementation Guide Version: 2 Release: 8 Benchmark Date: 01 Jul 2026:

NTLM must be prevented from falling back to a Null session.

DISA Rule

SV-253458r991589_rule

Vulnerability Number

V-253458

Group Title

SRG-OS-000480-GPOS-00227

Rule Version

WN11-SO-000180

Severity

CAT II

CCI(s)

• CCI-000366 - Implement the security configuration settings.

Weight

10

Fix Recommendation

Configure the policy value for Computer Configuration >> Windows Settings >> Security Settings >> Local Policies >> Security Options >> "Network security: Allow LocalSystem NULL session fallback" to "Disabled".

Check Contents

If the following registry value does not exist or is not configured as specified, this is a finding:

Registry Hive: HKEY_LOCAL_MACHINE
Registry Path: \SYSTEM\CurrentControlSet\Control\LSA\MSV1_0\

Value Name: allownullsessionfallback

Value Type: REG_DWORD
Value: 0

Vulnerability Number

V-253458

Documentable

False

Rule Version

WN11-SO-000180

Severity Override Guidance

If the following registry value does not exist or is not configured as specified, this is a finding:

Registry Hive: HKEY_LOCAL_MACHINE
Registry Path: \SYSTEM\CurrentControlSet\Control\LSA\MSV1_0\

Value Name: allownullsessionfallback

Value Type: REG_DWORD
Value: 0

Check Content Reference

M

Target Key

5471