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CVE-2026-56168· NVD / CVE Program· CNA microsoft

Windows SMB Server Denial of Service Vulnerability

Null pointer dereference in Windows SMB Server allows an authorized attacker to deny service over a network.

MediumCVSS 6.5 · v3.1—No exploit Fix available
Published
Jul 14, 2026
Updated
Oct 8, 2026
EPSS
1.1% · 66th percentile
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Action score

26

Monitor

Low priority for now.

CVSS
26 / 40 · 6.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 1.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · microsoft
6.5
NVD has not scored this yet; the score shown is the CNA’s.

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Noroxi analysis

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Affected systems

VendorProduct
microsoftwindows 10 21h2
microsoftwindows 10 22h2
microsoftwindows 11 24h2
microsoftwindows 11 25h2
microsoftwindows 11 26h1
microsoftwindows server 2022
microsoftwindows server 2025

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • microsoft windows server 2022before 10.0.20348.5386
  • microsoft windows server 2025before 10.0.26100.33158

Versions reported by the vendor

Affected version ranges reported by the assigning authority (microsoft). Independent of NVD's CPE analysis and usually ahead of it.

  • Microsoft Windows 10 Version 21H2

    • 10.0.19044.0 and later · before 10.0.19044.7548affected

  • Microsoft Windows 10 Version 22H2

    • 10.0.19045.0 and later · before 10.0.19045.7548affected

  • Microsoft Windows 11 Version 24H2

    • 10.0.26100.0 and later · before 10.0.26100.8875affected

  • Microsoft Windows 11 Version 25H2

    • 10.0.26200.0 and later · before 10.0.26200.8875affected

  • Microsoft Windows 11 version 26H1

    • 10.0.28000.0 and later · before 10.0.28000.2525affected

  • Microsoft Windows Server 2022

    • 10.0.20348.0 and later · before 10.0.20348.5386affected

  • Microsoft Windows Server 2025

    • 10.0.26100.0 and later · before 10.0.26100.33158affected

  • Microsoft Windows Server 2025 (Server Core installation)

    • 10.0.26100.0 and later · before 10.0.26100.33158affected

Same product

microsoft: all records

Other highest-scoring records for the same primary product.

  • CVE-2025-21333Windows Hyper-V NT Kernel Integration VSP Elevation of Privilege VulnerabilityKEV
    64This week
  • CVE-2025-21335Windows Hyper-V NT Kernel Integration VSP Elevation of Privilege VulnerabilityKEV
    61This week
  • CVE-2025-21334Windows Hyper-V NT Kernel Integration VSP Elevation of Privilege VulnerabilityKEV
    61This week
  • CVE-2023-38186Windows Mobile Device Management Elevation of Privilege Vulnerability
    39Monitor
  • CVE-2026-42904Windows TCP/IP Elevation of Privilege Vulnerability
    38Monitor
  • CVE-2023-38148Internet Connection Sharing (ICS) Remote Code Execution Vulnerability
    37Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Windows 10 Version 21H2 for 32-bit Systems10.0.19044.7548 · KB5099539Microsoft (MSRC)
Windows 10 Version 21H2 for ARM64-based Systems10.0.19044.7548 · KB5099539Microsoft (MSRC)
Windows 10 Version 21H2 for x64-based Systems10.0.19044.7548 · KB5099539Microsoft (MSRC)
Windows 10 Version 22H2 for 32-bit Systems10.0.19045.7548 · KB5099539Microsoft (MSRC)
Windows 10 Version 22H2 for ARM64-based Systems10.0.19045.7548 · KB5099539Microsoft (MSRC)
Windows 10 Version 22H2 for x64-based Systems10.0.19045.7548 · KB5099539Microsoft (MSRC)
Windows 11 Version 24H2 for ARM64-based Systems10.0.26100.8875 · KB5101650Microsoft (MSRC)
Windows 11 Version 24H2 for x64-based Systems10.0.26100.8875 · KB5101650Microsoft (MSRC)
Windows 11 Version 25H2 for ARM64-based Systems10.0.26200.8875 · KB5101650Microsoft (MSRC)
Windows 11 Version 25H2 for x64-based Systems10.0.26200.8875 · KB5101650Microsoft (MSRC)
Windows 11 Version 26H1 for ARM64-based Systems10.0.28000.2525 · KB5101649Microsoft (MSRC)
Windows 11 version 26H1 for x64-based Systems10.0.28000.2525 · KB5101649Microsoft (MSRC)
Windows Server 202210.0.20348.5386 · KB5099540Microsoft (MSRC)
Windows Server 202510.0.26100.33158 · KB5099536Microsoft (MSRC)
Windows Server 2025 (Server Core installation)10.0.26100.33158 · KB5099536Microsoft (MSRC)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-6270228 days apartWindows Graphics Kernel Denial of Service Vulnerability
    34Monitor
  • CVE-2026-24293126 days apartWindows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability
    31Monitor
  • CVE-2025-62463217 days apartDirectX Graphics Kernel Denial of Service Vulnerability
    26Monitor
  • CVE-2025-24997490 days apartDirectX Graphics Kernel File Denial of Service Vulnerability
    17Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-476 · NULL Pointer Dereference

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records