CVE-2024-53103: Linux Kernel Use-After-Free Vulnerability

CVE-2024-53103 Overview

CVE-2024-53103 is a Use After Free vulnerability in the Linux kernel's Hyper-V socket (hv_sock) implementation. The vulnerability exists in the handling of the vsk->trans pointer during the release of hvs (Hyper-V socket) connections. When the hvs structure is released, there is a possibility that the vsk->trans pointer may not be properly initialized to NULL, resulting in a dangling pointer condition that could be exploited by a local attacker.

Critical Impact

A local attacker with low privileges could potentially exploit this dangling pointer vulnerability to achieve privilege escalation, execute arbitrary code, or cause system instability on affected Linux systems running Hyper-V socket functionality.

Affected Products

• Linux Kernel versions prior to patched releases
• Linux Kernel 6.12 release candidates (rc1 through rc7)
• Linux Kernel 6.12 base version

Discovery Timeline

• December 2, 2024 - CVE-2024-53103 published to NVD
• November 3, 2025 - Last updated in NVD database

Technical Details for CVE-2024-53103

Vulnerability Analysis

This vulnerability is classified as CWE-416 (Use After Free). The flaw resides in the Linux kernel's hv_sock module, which provides socket communication capabilities for Hyper-V virtual machines. The core issue stems from improper memory management during socket cleanup operations.

When a Hyper-V socket connection is released, the transport layer structure (vsk->trans) should be properly nullified to prevent any subsequent code from accessing freed memory. However, in vulnerable kernel versions, this initialization step may be skipped under certain conditions, leaving the pointer in an undefined state pointing to potentially deallocated memory.

An attacker with local access could potentially trigger this condition by manipulating socket operations, then leverage the dangling pointer to achieve memory corruption. Given the local attack vector and low privilege requirements, exploitation would typically require the attacker to already have a foothold on the target system.

Root Cause

The root cause is the failure to properly initialize the vsk->trans pointer to NULL during the hvs release process. In C programming, failing to nullify pointers after freeing associated memory is a common source of use-after-free vulnerabilities. The fix is straightforward: explicitly setting vsk->trans = NULL during the cleanup path ensures that any subsequent access attempts will result in a null pointer dereference (which is typically caught) rather than accessing freed memory (which could be exploited).

Attack Vector

The attack vector is local, meaning an attacker must have local access to the system to exploit this vulnerability. The exploitation scenario involves:

1. A local attacker with low-level privileges triggers the creation and release of Hyper-V socket connections
2. Through precise timing or repeated operations, the attacker can cause the vsk->trans pointer to remain uninitialized
3. The attacker then triggers code paths that attempt to access the dangling pointer
4. If successful, this could lead to memory corruption, information disclosure, or arbitrary code execution with kernel privileges

The vulnerability primarily affects systems using Hyper-V virtualization where the hv_sock module is loaded and actively used for VM communication.

Detection Methods for CVE-2024-53103

Indicators of Compromise

• Unexpected kernel crashes or panics related to the hv_sock module or vsock subsystem
• Unusual memory access violations in kernel logs referencing hv_sock or transport layer structures
• Elevated privilege processes spawning from unprivileged user contexts on Hyper-V enabled systems
• System instability specifically during Hyper-V socket connection teardown operations

Detection Strategies

• Monitor kernel logs (dmesg, /var/log/kern.log) for any crashes or warnings related to hv_sock, vsock, or transport layer null pointer issues
• Implement kernel address sanitizer (KASAN) in development/testing environments to detect use-after-free conditions
• Use SentinelOne's kernel-level monitoring to detect anomalous memory access patterns in the hv_sock subsystem
• Deploy audit rules to track socket creation and destruction events on Hyper-V enabled systems

Monitoring Recommendations

• Enable kernel tracing for vsock and hv_sock subsystems to capture detailed connection lifecycle events
• Configure alerts for repeated socket creation/destruction patterns that could indicate exploitation attempts
• Monitor for processes attempting to load or interact with the hv_sock module in unexpected ways
• Review system stability logs on Hyper-V VMs for unexplained restarts or kernel panics

How to Mitigate CVE-2024-53103

Immediate Actions Required

• Update the Linux kernel to a patched version that includes the fix for CVE-2024-53103
• For systems that cannot be immediately patched, consider disabling the hv_sock module if Hyper-V socket functionality is not required
• Restrict local access to systems running vulnerable kernel versions to trusted users only
• Monitor affected systems closely for signs of exploitation until patches can be applied

Patch Information

The Linux kernel maintainers have released patches across multiple stable kernel branches. The fix initializes vsk->trans to NULL to prevent the dangling pointer condition. Patches are available through the following kernel git commits:

• Kernel Patch e629295bd60a
• Kernel Patch e0fe33923712
• Kernel Patch 98d8dde92322
• Kernel Patch 8621725afb38

Debian users should refer to the Debian LTS Security Announcements for distribution-specific updates.

Workarounds

• Disable the hv_sock kernel module using modprobe -r hv_sock if Hyper-V socket communication is not required for your workload
• Apply network segmentation to limit local access vectors to Hyper-V enabled systems
• Use mandatory access control systems (SELinux, AppArmor) to restrict which processes can interact with Hyper-V socket interfaces
• Consider running critical workloads on non-Hyper-V virtualization platforms until patching is complete

# Disable hv_sock module temporarily
sudo modprobe -r hv_sock

# Prevent hv_sock from loading at boot
echo "blacklist hv_sock" | sudo tee /etc/modprobe.d/blacklist-hv_sock.conf

# Verify module is not loaded
lsmod | grep hv_sock