CVE-2023-53686
📋 TL;DR
A null pointer dereference vulnerability in the Linux kernel's handshake netlink subsystem allows local attackers to cause a kernel panic (denial of service) or potentially execute arbitrary code. This affects systems running vulnerable Linux kernel versions with the handshake functionality enabled. Attackers need local access to exploit this vulnerability.
💻 Affected Systems
- Linux Kernel
📦 What is this software?
Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →⚠️ Risk & Real-World Impact
Worst Case
Kernel panic leading to system crash and denial of service; potential for privilege escalation or arbitrary code execution if combined with other vulnerabilities.
Likely Case
Local denial of service through kernel panic, requiring system reboot to recover.
If Mitigated
Minimal impact if handshake functionality is disabled or systems are properly patched.
🎯 Exploit Status
Exploitation requires local access and knowledge of triggering the handshake_nl_done_doit() function with specific parameters; kernel debugging symbols or source code analysis needed for reliable exploitation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Fixed in kernel commits 82ba0ff7bf0483d962e592017bef659ae022d754 and 93d69f18edcca282351394c5870bec24cc99d745
Vendor Advisory: https://git.kernel.org/stable/c/82ba0ff7bf0483d962e592017bef659ae022d754
Restart Required: Yes
Instructions:
1. Update Linux kernel to version containing fixes 2. Rebuild kernel if compiling from source 3. Reboot system to load new kernel
🔧 Temporary Workarounds
Disable handshake functionality
allDisable CONFIG_TLS_HANDSHAKE kernel configuration option to remove vulnerable code path
Rebuild kernel with CONFIG_TLS_HANDSHAKE=n
🧯 If You Can't Patch
- Restrict local user access to systems where handshake functionality is required
- Implement strict privilege separation and monitor for suspicious local process behavior
🔍 How to Verify
Check if Vulnerable:
Check kernel version and configuration: 'uname -r' and verify if CONFIG_TLS_HANDSHAKE is enabled in /boot/config-$(uname -r)Check Version:
uname -rVerify Fix Applied:
Verify kernel version includes fixes: check git commit history or kernel changelog for commits 82ba0ff7bf0483d962e592017bef659ae022d754 and 93d69f18edcca282351394c5870bec24cc99d745📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages mentioning 'handshake_nl_done_doit'
- KASAN null-ptr-deref reports in kernel logs
- System crash/reboot events
Network Indicators:
- No network indicators - local vulnerability only
SIEM Query:
source="kernel" AND ("handshake_nl_done_doit" OR "null-ptr-deref" OR "KASAN")