CVE-2026-50299: Windows 10 1607 RCE Vulnerability

CVE-2026-50299 Overview

CVE-2026-50299 is an integer overflow vulnerability in Microsoft Windows Storage Spaces Direct (S2D). An attacker with physical access to an affected system can trigger the flaw to execute arbitrary code on the host. The weakness is classified under [CWE-122] (Heap-based Buffer Overflow), where an integer wraparound leads to an undersized heap allocation and subsequent memory corruption. Microsoft has published an advisory tracked in the Microsoft Security Response Center update guide. The vulnerability affects a broad set of Windows client and server versions, including Windows 10, Windows 11, and Windows Server releases from 2012 R2 through Windows Server 2025.

Critical Impact
Successful exploitation grants code execution with full confidentiality, integrity, and availability impact on the affected Storage Spaces Direct node.

Affected Products

Microsoft Windows 10 (versions 1607, 1809, 21H2, 22H2) across x86, x64, and ARM64 builds
Microsoft Windows 11 (versions 24H2, 25H2, 26H1) across x64 and ARM64 builds
Microsoft Windows Server 2012 R2, 2016, 2019, 2022, and 2025

Discovery Timeline

2026-07-14 - CVE-2026-50299 published to the National Vulnerability Database
2026-07-16 - Last updated in NVD database

Technical Details for CVE-2026-50299

Vulnerability Analysis

Storage Spaces Direct is a Windows feature that pools direct-attached storage across servers to build software-defined storage clusters. The component processes on-disk and in-memory metadata structures that describe pools, virtual disks, and slab layouts. CVE-2026-50299 arises when this code performs arithmetic on attacker-influenced size or count fields without validating the result against representable integer bounds.

When the arithmetic wraps, a subsequent heap allocation is sized incorrectly. The affected routine then writes attacker-controlled data past the end of the smaller-than-expected buffer, corrupting adjacent heap structures. Controlled heap corruption in kernel or driver context allows an attacker to hijack execution flow and run arbitrary code on the affected node.

Root Cause

The root cause is an integer overflow or wraparound in a length or count calculation used to allocate a heap buffer inside the Storage Spaces Direct code path. Because bounds checks occur on the pre-overflow value rather than on the multiplication or addition result, the allocator returns a buffer smaller than the data eventually copied into it, producing a heap-based buffer overflow.

Attack Vector

Exploitation requires physical access to the target machine, as indicated by the AV:P attack vector. No authentication or user interaction is needed. A practical attack path involves connecting a crafted storage device or interacting directly with the storage subsystem so that Storage Spaces Direct parses malformed metadata during enumeration or pool operations. Because the flaw is reachable at a low privilege boundary, exploitation yields code execution with high impact to confidentiality, integrity, and availability.

No public proof-of-concept code is available, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. The current EPSS probability is 0.327%.

Detection Methods for CVE-2026-50299

Indicators of Compromise

Unexpected crashes, bugchecks, or restarts of the clusssvc service or Storage Spaces Direct components on cluster nodes.
Kernel or driver faults referencing spaceport.sys, clusport.sys, or related storage stack modules in Windows Error Reporting data.
Newly connected or replaced physical storage devices immediately followed by pool enumeration errors in the System event log.

Detection Strategies

Monitor Windows event channels Microsoft-Windows-StorageSpaces-Driver/Operational and Microsoft-Windows-FailoverClustering/Operational for anomalous errors around pool, slab, or virtual disk operations.
Correlate physical access events (chassis intrusion, hot-plug of drives, USB storage enumeration) with subsequent storage subsystem faults.
Baseline patch state across the cluster and alert on nodes running unpatched builds of the affected Windows versions.

Monitoring Recommendations

Enable and centrally collect kernel crash dumps from Storage Spaces Direct nodes and inspect for heap corruption signatures.
Track physical console and out-of-band management (BMC, iDRAC, iLO) sessions on cluster hosts to identify unauthorized physical interaction.
Alert on unplanned failover events initiated by node bugchecks rather than administrative action.

How to Mitigate CVE-2026-50299

Immediate Actions Required

Apply the Microsoft security updates referenced in the Microsoft CVE-2026-50299 Advisory to all affected Windows 10, Windows 11, and Windows Server systems.
Prioritize patching on any host that participates in a Storage Spaces Direct cluster or has the feature enabled.
Audit and restrict physical and out-of-band access to storage cluster nodes until patches are deployed.

Patch Information

Microsoft has issued fixes through its standard security update channels. Refer to the Microsoft CVE-2026-50299 Advisory for the specific KB articles and cumulative update numbers that correspond to each affected Windows 10, Windows 11, and Windows Server build.

Workarounds

Enforce strict physical security controls on cluster nodes, including locked racks, tamper-evident seals, and controlled datacenter access.
Disable hot-plug of untrusted storage devices where operationally feasible and require change control for any physical drive additions.
Where Storage Spaces Direct is not required, disable the feature on affected hosts until updates can be validated and deployed.

bash

# Verify whether the Storage Spaces Direct feature is enabled on a node
Get-ClusterStorageSpacesDirect

# List installed updates to confirm the CVE-2026-50299 patch is present
Get-HotFix | Sort-Object -Property InstalledOn -Descending