CVE-2026-35419: Windows 11 24h2 Information Disclosure

CVE-2026-35419 Overview

CVE-2026-35419 is an out-of-bounds read vulnerability in the Windows Desktop Window Manager (DWM) Core Library. The flaw allows an authorized local attacker to disclose sensitive information from process memory. Exploitation requires local access and low-level user privileges, with no user interaction needed. The vulnerability affects multiple supported Windows 11 releases and Windows Server 2025. Microsoft has issued a security advisory through MSRC tracking this issue under CVE-2026-35419.

Critical Impact

An authenticated local attacker can read memory outside intended bounds within the DWM Core Library, leaking confidential data such as memory pointers, address layout information, or process state that may aid further exploitation.

Affected Products

• Microsoft Windows 11 24H2 (x64 and ARM64)
• Microsoft Windows 11 25H2 (x64 and ARM64)
• Microsoft Windows 11 26H1 (x64 and ARM64) and Windows Server 2025

Discovery Timeline

• 2026-05-12 - CVE-2026-35419 published to NVD
• 2026-05-14 - Last updated in NVD database

Technical Details for CVE-2026-35419

Vulnerability Analysis

The vulnerability resides in the Windows DWM Core Library (dwmcore.dll), the component responsible for compositing graphical output for the Windows desktop. The library handles rendering surfaces, window thumbnails, animations, and visual effects for every interactive session. An out-of-bounds read [CWE-125] occurs when DWM Core processes a crafted input or graphics object and accesses memory beyond the bounds of an allocated buffer.

Because DWM runs as part of the active user session, leaked memory may include data from rendered windows, GDI structures, or DWM internal state. The attacker gains confidentiality impact only; integrity and availability remain unaffected per the CVSS vector. The flaw cannot be triggered remotely and requires the attacker to already hold a valid logon to the target host.

Root Cause

The underlying defect is improper validation of length or index values when DWM Core reads from a memory buffer. When the bounds check is missing or incorrect, the library returns adjacent heap or stack contents to the caller. Microsoft has not published the specific function involved. Refer to the Microsoft Security Update CVE-2026-35419 advisory for fix details.

Attack Vector

An attacker must execute code locally on the target system as an authenticated user. The actor then interacts with DWM Core Library interfaces, likely through a graphics or compositing API call, to trigger the read past buffer boundaries. The leaked bytes can be used to bypass Address Space Layout Randomization (ASLR) or chain with another vulnerability to achieve privilege escalation. No public proof-of-concept exploit is currently available, and the issue is not listed on the CISA Known Exploited Vulnerabilities catalog.

No verified exploitation code is available. The vulnerability mechanism is described in prose above; consult the Microsoft advisory for the authoritative technical description.

Detection Methods for CVE-2026-35419

Indicators of Compromise

• No public indicators of compromise have been published for CVE-2026-35419 at this time.
• Unexpected crashes or access violations in dwm.exe or processes loading dwmcore.dll may indicate exploitation attempts.
• Unusual local process activity reading from DWM shared sections or compositor APIs from non-graphical user processes.

Detection Strategies

• Monitor for unsigned or unusual binaries invoking DWM-related APIs or attempting to interact with the compositor from non-interactive sessions.
• Correlate local logon events with subsequent abnormal process behavior targeting graphics subsystems.
• Track Windows Error Reporting (WER) records and crash dumps referencing dwmcore.dll for repeated faults in the same module offset.

Monitoring Recommendations

• Enable process creation auditing (Event ID 4688) and Sysmon Event ID 7 to surface unexpected modules loaded by user-mode processes.
• Centralize endpoint telemetry and apply behavioral rules that flag information disclosure patterns following recent local logons.
• Alert on installation of unsigned drivers or graphics-related tools on systems that have not yet received the May 2026 cumulative update.

How to Mitigate CVE-2026-35419

Immediate Actions Required

• Apply the Microsoft security update referenced in the MSRC advisory for CVE-2026-35419 to all affected Windows 11 24H2, 25H2, 26H1, and Windows Server 2025 endpoints.
• Prioritize patching multi-user systems, Remote Desktop Session Hosts, and Virtual Desktop Infrastructure (VDI) hosts where multiple authenticated users share a single machine.
• Restrict interactive and remote interactive logon rights to trusted administrators on sensitive servers until patches are deployed.

Patch Information

Microsoft published the fix as part of the security update cycle covered by the Microsoft Security Update CVE-2026-35419 advisory. Install the cumulative update for the applicable Windows 11 channel (24H2, 25H2, or 26H1) or Windows Server 2025 build through Windows Update, WSUS, Microsoft Update Catalog, or your preferred patch management platform. Reboot the system after installation to load the updated dwmcore.dll.

Workarounds

• No vendor-supplied workaround has been published; applying the security update is the only supported remediation.
• Reduce the local attack surface by removing unnecessary local accounts and enforcing least-privilege policies on shared hosts.
• Use application control policies such as Windows Defender Application Control (WDAC) or AppLocker to block execution of unauthorized binaries by standard users.

# Verify the affected DLL version after patching (run in elevated PowerShell)
Get-Item C:\Windows\System32\dwmcore.dll | Select-Object VersionInfo

# Confirm the latest cumulative update is installed
Get-HotFix | Sort-Object -Property InstalledOn -Descending | Select-Object -First 5