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Microsoft Windows Storage Spaces Controller: Heap-based buffer overflow enables local privilege escalation

CVE-2026-70238High 7.8

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Summary

A heap-based buffer overflow in the Windows Storage Spaces Controller allows an authenticated local user to elevate privileges on the affected system. The vulnerability is rated High (CVSS 3.1 7.8) and requires local access and a low-privilege account. An attacker would typically need a foothold first, such as a phished or stolen account or malware, before exploiting it.

Affected

  • Windows 10 Version 1607 (builds below 10.0.14393.9612), according to the CNA record
  • Windows Server 2016 (builds below 10.0.14393.9612), according to the CNA record
  • Other Windows 10, Windows 11 and Windows Server versions are listed in conflicting sources; verify on the MSRC advisory before relying on any version number.

Fixed in

  • Fixed builds are not confirmed in the sources reviewed. Verify on the MSRC advisory.
  • Tenable entries found for October 2026 cover Windows Server 2025 (KB5126646) and Windows 10 1809/Server 2019 (KB5126651) only.
  • No confirmed fix found for Windows 10 1607.

Workaround

  • According to a third-party aggregator (OpenCVE, truncated), if patching is not possible immediately, the Windows Storage Spaces feature can be disabled or its service restricted. This is not confirmed by MSRC; verify before use.

Exploitation

  • No evidence of exploitation in the wild or public proof of concept found.
  • EPSS is about 0.35%, a low predicted probability, not a confirmed status.
  • Microsoft Exploitability Index and CISA KEV status: not found. CISA SSVC: Exploitation none, Automatable no, Technical Impact total.

Our recommendation

  • Inventory all systems with Windows 10 1607 and check whether Storage Spaces is in use.
  • Plan migration of Windows 10 1607 hosts, as no standard fix may be available for this end-of-support build.
  • Patch Windows Server 2016 and newer systems with Storage Spaces in the normal monthly cycle, after checking the MSRC advisory for the correct builds.
  • Restrict local logon to trusted users and monitor for privilege escalation activity.
  • Check the related CVEs in the same component (CVE-2026-69575, EUVD-2026-73683).

Information from Microsoft (Patch Tuesday October 2026)

Severity (Microsoft)
Important
Impact
Elevation of privilege – Windows Storage Spaces Controller
Status on Patch Tuesday
Neither exploited nor publicly disclosed
Exploitability assessment
Exploitation less likely
Product family
Windows, Windows ESU (Extended Security Updates)
Updates (KB)
KB5126651, KB5126655, KB5126657, KB5126646, KB5127648, KB5126653

Entry in the Microsoft Security Update Guide

Public exploits

PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.

Research sources

Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 2 Nov 2026, 03:55.

Original description (NVD)

Heap-based buffer overflow in Windows Storage Spaces Controller allows an authorized attacker to elevate privileges locally.

NVD references (1)

Sources

The tracker combines official, freely usable data sources – updated continuously:

This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.

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