CVE-2025-27475 Overview
CVE-2025-27475 is a local privilege escalation vulnerability in the Windows Update Stack. Microsoft reports that sensitive data is stored in improperly locked memory [CWE-591], allowing an authorized attacker to read memory contents and elevate privileges. The vulnerability affects Windows 11 versions 22H2, 23H2, and 24H2. Exploitation requires local access and low-level privileges, but no user interaction. Successful exploitation impacts confidentiality, integrity, and availability of the affected system.
Critical Impact
An authenticated local attacker can elevate privileges on affected Windows 11 systems by extracting sensitive data from memory regions that lack proper locking protections.
Affected Products
- Microsoft Windows 11 22H2
- Microsoft Windows 11 23H2
- Microsoft Windows 11 24H2
Discovery Timeline
- 2025-04-08 - CVE-2025-27475 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-27475
Vulnerability Analysis
The vulnerability resides in the Windows Update Stack, a privileged component responsible for downloading, validating, and applying operating system updates. The stack stores sensitive data in memory regions that are not properly locked. This weakness maps to [CWE-591] Sensitive Data Storage in Improperly Locked Memory. An authorized local attacker with low privileges can access that memory and use its contents to elevate to higher privileges on the host.
The attack complexity is rated as high, which indicates the attacker must satisfy specific conditions or win a race with the Update Stack process. The vulnerability does not require user interaction. Because the Windows Update Stack operates with elevated rights, successful memory access can yield credentials, tokens, or update-signing material that unlocks broader system control.
Root Cause
The root cause is the failure to lock or protect memory pages that hold sensitive data used by the Windows Update Stack. Memory that is not locked can be paged, inspected, or accessed by a concurrent process, exposing secrets that should remain isolated in the privileged process context.
Attack Vector
Exploitation requires local authenticated access to the target Windows 11 system. The attacker runs code as a low-privileged user and targets the Update Stack process during a window when sensitive material is present in unprotected memory. Refer to the Microsoft CVE-2025-27475 Advisory for vendor-authored technical details.
No public proof-of-concept code has been published, and Microsoft has not confirmed exploitation in the wild.
Detection Methods for CVE-2025-27475
Indicators of Compromise
- Unexpected child processes spawned by wuauclt.exe, UsoClient.exe, or the TrustedInstaller service.
- Non-Microsoft processes opening handles to Windows Update Stack processes with PROCESS_VM_READ access rights.
- New local administrator accounts or SYSTEM-level scheduled tasks created shortly after Update Stack activity.
Detection Strategies
- Monitor Sysmon Event ID 10 (ProcessAccess) for cross-process memory reads targeting Windows Update Stack binaries from non-system callers.
- Correlate token elevation events (Windows Security Event 4672) with recent Update Stack activity from unprivileged user sessions.
- Baseline Windows Update service behavior and alert on deviations such as unusual DLL loads or off-hours execution.
Monitoring Recommendations
- Enable PowerShell and command-line auditing to capture post-exploitation activity following any elevation event.
- Forward Windows Update, Security, and Sysmon logs to a centralized SIEM for correlation across endpoints.
- Track patch state of Windows 11 22H2, 23H2, and 24H2 hosts and flag systems that miss the April 2025 cumulative update.
How to Mitigate CVE-2025-27475
Immediate Actions Required
- Apply the Microsoft security update referenced in the Microsoft CVE-2025-27475 Advisory to all affected Windows 11 systems.
- Inventory Windows 11 22H2, 23H2, and 24H2 endpoints and prioritize patching for systems accessible to standard users.
- Restrict interactive and remote logon rights on sensitive systems to reduce the local attack surface.
Patch Information
Microsoft has released updates addressing CVE-2025-27475 through the Windows Update channel. Administrators should deploy the latest cumulative update for Windows 11 22H2, 23H2, and 24H2 via Windows Update, WSUS, or Microsoft Intune. See the Microsoft CVE-2025-27475 Advisory for build numbers and KB identifiers.
Workarounds
- No official workaround has been published by Microsoft; patching remains the required mitigation.
- Enforce the principle of least privilege and remove local administrator rights from standard user accounts.
- Apply application control policies such as Windows Defender Application Control to block unauthorized binaries from executing on affected hosts.
# Verify installed cumulative update on Windows 11
wmic qfe list brief /format:table
# Trigger Windows Update scan and installation
UsoClient StartScan
UsoClient StartDownload
UsoClient StartInstall
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
