STIGQter: STIG Summary: Microsoft Windows Server 2025 Security Technical Implementation Guide Version: 1 Release: 2 Benchmark Date: 01 Jul 2026:

Windows Server 2025 must prevent NTLM from falling back to a Null session.

DISA Rule

SV-278221r1181369_rule

Vulnerability Number

V-278221

Group Title

SRG-OS-000480-GPOS-00227

Rule Version

WN25-SO-000270

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

Type: REG_DWORD
Value: 0x00000000 (0)

Vulnerability Number

V-278221

Documentable

False

Rule Version

WN25-SO-000270

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

Type: REG_DWORD
Value: 0x00000000 (0)

Check Content Reference

M

Target Key

5719