CVE-2025-24983 is a critical vulnerability discovered in the Win32 kernel subsystem of Microsoft Windows. This flaw is classified as a "use-after-free", meaning memory that’s been freed is still used by the system — opening a dangerous window for attackers. Let's break down what this means, how attackers exploit it, and what you can do about it.

What is a Use-After-Free Vulnerability?

A use-after-free vulnerability happens when an application continues to use a pointer to memory after it has been freed. In kernel space, this can result in unexpected behavior, including arbitrary code execution.

Why is this dangerous in the Windows kernel?
Because the kernel is the heart of Windows. If an attacker can manipulate it, they can do nearly anything — especially if they already have local access to your machine.

How Does CVE-2025-24983 Work?

An attacker who can run code on the local system can trigger a scenario where certain Win32 subsystem kernel objects are freed but still accessed later. By carefully timing certain system calls, the attacker can manipulate what memory fills that space once it’s freed, effectively hijacking the system and escalating privileges.

Trigger a use-after-free: Free the object in a way the kernel isn’t expecting.

3. Fill the freed memory ("heap spray") with controlled data (like a structure containing code pointers).

Example Attack Scenario (Pseudo-Code)

Below is a simplified (and safe) pseudo-code example. This is for illustration only, not an attack script.

// Step 1: Create a vulnerable window object
HWND hwnd = CreateWindowEx(, "STATIC", "vuln", , , , 100, 100, , , , NULL);

// Step 2: Trigger a condition that frees it but pointer remains
DestroyWindow(hwnd);

// Step 3: Heap spray - allocate objects to fill freed space
for (int i = ; i < 10000; i++) {
    CreateMenu();
}

// Step 4: Kernel uses pointer to freed memory (attacker-controlled)
// (This is just to illustrate. Details depend on the actual bug)
SendMessage(hwnd, WM_USER, , ); // hwnd is now "dangling".

// If successful, code at the attacker's chosen address runs in kernel mode.

Note: Actual exploitation involves deep knowledge of Windows internals, precise timing, and bypassing kernel protections like KASLR and SMEP.

Demo Video

Watch a demonstration of local privilege escalation via a generic Windows kernel use-after-free:
https://www.youtube.com/watch?v=Yu5A53FZb94

Original References

- Microsoft Security Advisory for CVE-2025-24983
- ZDI Advisory for CVE-2025-24983
- FreeBuf Writeup – Windows Kernel Use-After-Free Privilege Escalation

Conclusion

CVE-2025-24983 shows how local bugs can lead to total system compromise. Always patch and stay informed! If you’re responsible for Windows systems, make sure they’re up to date — this is the kind of vulnerability attackers love.

Timeline

Published on: 03/11/2025 17:16:33 UTC
Last modified on: 03/13/2025 19:54:30 UTC