New Exploitation Method Discovered for Linux Kernel Use-After-Free Vulnerability

A new exploitation method has been discovered for the Linux kernel use-after-free (UAF) vulnerability tracked as CVE-2024-50264.

The vulnerability was awarded the Pwnie Award 2025 for Best Privilege Escalation due to its complexity and impact on major Linux distributions.

Researchers developed innovative techniques to bypass kernel slab allocator and race condition protections, making exploitation much more feasible than previously believed.

UAF Vulnerability Background

CVE-2024-50264 is a race condition in the AF_VSOCK subsystem, present in Linux kernels since version 4.8.

The bug allows an unprivileged attacker to trigger a use-after-free scenario in the virtio_vsock_sock object during socket connection operations.

This can occur without user namespace privileges, making the flaw highly dangerous. Exploitation is challenging because of kernel hardening such as randomized slab caches and SLAB buckets, which disrupt naive heap spraying and cross-cache attacks.

Breakthrough Exploit Techniques

The breakthrough came from using kernel-hack-drill, an open-source testing environment for Linux kernel exploits.

The new attack method combines several advanced exploitation primitives:

• Interrupting the vulnerable connect() syscall with an “immortal” POSIX signal to trigger the race condition reliably without killing the exploit process.
• Leveraging slab cache behavior to reclaim freed objects by cross-cache allocation, carefully manipulating timing to force the kernel to allocate attacker-controlled structures where vulnerable objects used to reside.
• Corrupting key kernel objects such as msg_msg and pipe_buffer for information leaks and arbitrary address read/write. Notably, the exploit abuses the message queue system to achieve out-of-bounds kernel memory reads, extracting sensitive pointers such as credentials.

This new exploitation method demonstrates that even hardened kernels remain susceptible to creative exploitation strategies.

Attackers can leverage race condition speedrun techniques to bypass object pairing and rapidly force vulnerable states.

The method also adapts typical privilege escalation tactics, such as the Dirty Pipe and Dirty Pagetable, to more restrictive environments.

As a result, the exploitation path is streamlined, increasing the risk of successful attacks on modern systems.

Security teams should treat CVE-2024-50264 as a major threat requiring urgent patching and review of kernel object hardening.

The kernel-hack-drill project now offers a valuable toolkit for researchers to develop and test kernel exploits, highlighting the need for ongoing security engineering in Linux internals.

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