Windows Win32K KASLR Bypass Information Disclosure, CVE-2026-50416 (LOW) -DC-Jul2026-1064

</code>.
From this single leaked QWORD, an attacker can recover the kernel desktop heap base and, using <code>gSharedInfo</code>, compute the exact kernel virtual address of every window, menu, and class object on the desktop. This effectively bypasses Kernel Address Space Layout Randomization (KASLR), a core exploit mitigation that randomizes kernel memory locations. While the leak itself does not grant code execution, it provides attackers with critical reconnaissance data that can be chained with other vulnerabilities to escalate privileges, harvest credentials, or extract cryptographic material from kernel memory.
The root cause is a missed sanitization step: Windows already uses a `0x6000000000` sentinel to sanitize kernel pointers elsewhere in this heap, but this specific field at offset `0x100` was overlooked. The vulnerability is local, requires low privileges, and no user interaction—making it a reliable primitive for sandbox escape and privilege escalation chains.

<h2 style="color: blue;">DailyCVE Form:</h2>

Platform: ....... Windows 11, Server 2025
Version: ........ 24H2, 25H2, 26H1, Server 2025
Vulnerability :...... KASLR bypass, info leak
Severity: ....... LOW (CVSS 3.3)
date: .......... 2026-07-14

<h2 style="color: blue;">Prediction: ...... Patch released (KB5101650)</h2>

<h2 style="color: blue;">What Undercode Say: Analytics</h2>

The vulnerability exposes a raw kernel pointer from the user-mode mapping of the win32k desktop heap. Below are the key analytical commands and proof-of-concept code snippets demonstrating the leak.

<h2 style="color: blue;">Retrieving the desktop heap address from TEB:</h2>

[bash]
PVOID teb = (PVOID)__readgsqword(0x30);
PVOID clientInfo = (PVOID)((BYTE)teb + 0x800);
BYTE desktopHeap = (BYTE)clientInfo[bash];

Source: GitHub writeup

Reading the leaked kernel pointer:

ULONG64 leaked = (ULONG64)(desktopHeap + 0x100);
// Example output: 0xFFFFA804DDE00040

Source: GitHub writeup

Verifying the pointer is canonical:

Check if the leaked address is a canonical kernel address
Top 17 bits should be set (0xFFFFxxxxxxxxxxxx)
echo "0xFFFFA804DDE00040" | grep -q "^0xFFFF" && echo "Canonical kernel pointer"

Identifying affected builds:

• Windows 11 Insider build 10.0.28020.2149
• Windows 11 24H2 (10.0.26100.0 < 10.0.26100.8875)
• Windows 11 25H2 (10.0.26200.0 < 10.0.26200.8875)
• Windows 11 26H1 (10.0.28000.0 < 10.0.28000.2525)
• Windows Server 2025 (10.0.26100.0 < 10.0.26100.33158)

Exploit primitive (sandbox readable):

// Any process with a desktop can read the leak, including:
// - Low integrity processes
// - AppContainers
// - LPAC with zero capabilities
// - Low integrity AppContainer (browser renderer sandbox)

Source: GitHub writeup

How Exploit:

Exploitation of CVE-2026-50416 is straightforward and does not require special privileges beyond the ability to execute code on the target system. An attacker would:
1. Obtain the desktop heap mapping address from the TEB `ClientInfo[bash]` field.
2. Read the QWORD at offset `0x100` of the desktop heap to retrieve the raw kernel session pool pointer.
3. Verify the pointer is a canonical kernel address (top 17 bits set) and eight-byte aligned.
4. Derive the kernel desktop heap base from the leaked pointer, as it points 0x40 bytes into the kernel-side desktop heap.
5. Combine with `gSharedInfo` to compute the virtual addresses of all window, menu, and class objects on the desktop.
The exploit is reliable across sandbox boundaries. The leak is readable from Low integrity processes, AppContainers, and LPAC containers with zero capabilities, including processes that mimic browser renderer sandboxes. A public proof-of-concept and writeup are available on GitHub.

Protection:

• Install the official Microsoft patch: KB5101650 for Windows 11 24H2/25H2, KB5101649 for Windows 11 26H1, and KB5099536 for Windows Server 2025.
• Apply the July 2026 cumulative updates released on Patch Tuesday (July 14, 2026).
• Enforce strict access controls and privilege separation policies to limit local attack surfaces.
• Monitor for anomalous memory access patterns or unauthorized data access attempts targeting kernel-mode components.
• Implement defense-in-depth with endpoint protection and network segmentation to detect and prevent exploitation attempts.
• Restrict local code execution where possible to reduce the attack surface for local information disclosure vulnerabilities.

Impact:

• Confidentiality Impact (Low): An authenticated local attacker can read sensitive kernel memory pointers, bypassing KASLR.
• Attack Vector: Local—requires the attacker to already have the ability to run code on the affected machine.
• Attack Complexity: Low—the leak is trivially accessible from any process with a desktop.
• Privileges Required: Low—the attacker does not need administrative rights.
• User Interaction: None—the vulnerability can be triggered without user involvement.
• Sandbox Escape Primitive: The leak is readable from Low integrity AppContainers, making it a valuable component in sandbox escape chains.
• Privilege Escalation Enabler: While not directly granting code execution, the KASLR bypass can be combined with memory corruption vulnerabilities to achieve SYSTEM-level access.
• Credential and Data Exposure: The leak can expose cached passwords, security tokens, and cryptographic material stored in kernel memory.
• No Network Entry: The vulnerability does not provide a remote attack vector.
• No Active Exploitation Reported: As of July 15, 2026, Microsoft had not observed active exploitation or public disclosure prior to the patch.

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Sources:

Reported By: nvd.nist.gov
Extra Source Hub:
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