EUVD-2026-44236
GHSA-2875-28w4-4vqx
Severity by source
AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
SMB is network-accessible; low-privilege authentication confirmed by 'authorized attacker' wording; availability-only impact with no confidentiality or integrity consequence.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
Null pointer dereference in Windows SMB Server allows an authorized attacker to deny service over a network.
AnalysisAI
Null pointer dereference in the Windows SMB Server component allows an authenticated network attacker to crash the service across multiple Windows 10, 11, and Server editions. The CVSS vector (AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H) confirms network exploitability with low-privilege credentials and complete availability impact, though confidentiality and integrity are unaffected. No public exploit identified at time of analysis; SSVC exploitation status is 'none' and EPSS sits at 0.79%, indicating low active exploitation pressure despite the broad product footprint.
Technical ContextAI
The vulnerability resides in the Windows SMB (Server Message Block) Server implementation, the protocol underpinning Windows file and printer sharing over TCP port 445. CWE-476 (Null Pointer Dereference) identifies the root cause as a failure to validate a pointer before dereferencing it during SMB network request processing - typically triggered when an edge case or malformed packet causes a parsing function to return null, which is subsequently used without a null check, causing an unhandled access violation. CPE data confirms the affected scope spans Windows 10 Version 21H2 and 22H2, Windows 11 Versions 24H2, 25H2, and 26H1, and Windows Server 2022 and 2025 (including Server Core installations). The crash impacts the SMB Server service, disrupting file sharing, authentication, and related Windows networking functions on the target host.
RemediationAI
Apply the Microsoft-released security update documented at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-56168. Fixed build targets per EUVD data are: Windows 10 21H2 - build 10.0.19044.7548 or later; Windows 10 22H2 - build 10.0.19045.7548 or later; Windows 11 24H2 - build 10.0.26100.8875 or later; Windows 11 25H2 - build 10.0.26200.8875 or later; Windows 11 26H1 - build 10.0.28000.2269 or later; Windows Server 2022 - build 10.0.20348.5386 or later; Windows Server 2025 and Server Core - build 10.0.26100.33158 or later. As a compensating control where immediate patching is not feasible, restrict inbound TCP port 445 access to only trusted hosts and subnets using host-based firewall rules or network segmentation - note this may break legitimate SMB-dependent services such as domain file shares and DFS. If SMB Server is not required on a given host, disabling the LanmanServer service entirely eliminates the attack surface with no impact on SMB Client functionality.
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Same weakness CWE-476 – NULL Pointer Dereference
View allSame technique Null Pointer Dereference
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External POC / Exploit Code
Leaving vuln.today