CVE-2026-69770: Windows Spaceport.sys Information Disclosure

CVE-2026-69770 is an information disclosure vulnerability in Windows Spaceport.sys caused by use of uninitialized resources. Authorized attackers can exploit this flaw locally to access sensitive data. This article covers technical details, affected Windows versions, potential impact, and recommended mitigation strategies.

CVE-2026-69770 Overview

CVE-2026-69770 is an information disclosure vulnerability in the Windows Spaceport driver (Spaceport.sys). The flaw stems from the use of an uninitialized resource [CWE-908], which allows an authenticated local attacker to read memory contents that were not properly cleared before use. Microsoft documented the issue in the Microsoft Security Update Guide.

Successful exploitation exposes kernel or driver memory data to a user-mode process. Attackers can chain this information leak with other vulnerabilities to defeat mitigations such as Kernel Address Space Layout Randomization (KASLR).

Critical Impact
An authorized local attacker can disclose sensitive memory contents from the Windows Storage Spaces (Spaceport) driver, aiding follow-on privilege escalation attempts.

Affected Products

Microsoft Windows (Spaceport.sys driver component)
Windows Storage Spaces subsystem
See the Microsoft Security Update Guide for the full list of affected builds

Discovery Timeline

2026-09-08 - CVE-2026-69770 published to NVD
2026-09-08 - Last updated in NVD database

Technical Details for CVE-2026-69770

Vulnerability Analysis

The vulnerability resides in Spaceport.sys, the kernel-mode driver that implements Windows Storage Spaces. The driver allocates a resource but fails to initialize its contents before returning data across a trust boundary. When a local user issues a crafted request that consumes this resource, residual memory from prior allocations is disclosed.

The exposed data can include kernel pointers, cryptographic material, or fragments of other processes' memory. This class of flaw is tracked under [CWE-908: Use of Uninitialized Resource] and is a common building block for privilege escalation chains on Windows.

Exploitation requires local access with valid credentials. No user interaction is needed, and the attack complexity is low. The scope is limited to confidentiality; integrity and availability are not directly affected.

Root Cause

The driver code path allocates a buffer or structure without zeroing its contents (for example, omitting RtlZeroMemory after ExAllocatePool2 with a non-zeroing flag, or reusing a stack structure without initialization). When the driver copies this resource to a user-accessible location, the uninitialized bytes leak.

Attack Vector

An authenticated attacker executes code on the target Windows system and issues IOCTL requests or API calls that reach the vulnerable Spaceport.sys code path. The driver returns a response containing uninitialized memory, which the attacker parses for sensitive values. Refer to the Microsoft Security Update Guide for technical specifics as they become available.

Detection Methods for CVE-2026-69770

Indicators of Compromise

Unexpected user-mode processes opening handles to Storage Spaces device objects such as \\.\Spaceport
Anomalous IOCTL traffic targeting Spaceport.sys from non-administrative processes
Presence of known proof-of-concept binaries or scripts referencing Storage Spaces interfaces

Detection Strategies

Enable kernel auditing for driver interactions and correlate handle-open events against a baseline of legitimate Storage Spaces management activity
Hunt for processes that read large buffers from Spaceport device handles without corresponding administrative context
Monitor for local privilege escalation patterns that follow suspicious driver interactions, since information disclosure is often chained with an elevation-of-privilege exploit

Monitoring Recommendations

Forward Windows Security and Sysmon event logs to a centralized analytics platform for correlation across endpoints
Track patch compliance for the September 2026 Microsoft security update on all Windows hosts running Storage Spaces
Alert on new drivers loaded on systems where Storage Spaces is unused, as this may indicate exploitation tooling

How to Mitigate CVE-2026-69770

Immediate Actions Required

Apply the Microsoft security update referenced in the Microsoft Security Update Guide to all affected Windows systems
Prioritize patching on multi-user systems, terminal servers, and virtual desktop infrastructure where local access is broader
Review local account inventories and remove unnecessary interactive logon rights

Patch Information

Microsoft released a security update addressing CVE-2026-69770. Administrators should deploy the update through Windows Update, Windows Server Update Services (WSUS), or Microsoft Endpoint Configuration Manager. Consult the Microsoft Security Update Guide for the specific KB article and build numbers.

Workarounds

Restrict local logon rights to trusted administrative accounts where feasible
Apply application control policies such as Windows Defender Application Control (WDAC) to block unauthorized binaries from executing on managed endpoints
Disable Storage Spaces on systems that do not require it, reducing the reachable attack surface of Spaceport.sys

bash

# Verify installed Windows updates on an affected host
wmic qfe list brief /format:table

# PowerShell alternative to list recent hotfixes
Get-HotFix | Sort-Object -Property InstalledOn -Descending | Select-Object -First 20