CVE-2023-53020
📋 TL;DR
This CVE describes a race condition vulnerability in the Linux kernel's L2TP (Layer 2 Tunneling Protocol) implementation. The vulnerability allows potential denial of service or kernel crashes due to improper locking when registering L2TP tunnels. It affects systems running vulnerable Linux kernel versions with L2TP functionality enabled.
💻 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 →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 →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 →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 →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 →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 →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 or system crash leading to complete denial of service, potentially requiring physical access to restart affected systems.
Likely Case
System instability, kernel crashes, or denial of service affecting L2TP tunnel functionality.
If Mitigated
Minimal impact if L2TP is not used or if proper kernel hardening is in place.
🎯 Exploit Status
Exploitation requires race condition triggering which is timing-dependent and complex. No public exploits known at this time.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions containing commits 0b2c59720e65885a394a017d0cf9cab118914682, 2d77e5c0ad79004b5ef901895437e9cce6dfcc7e, 77e8ed776cdb1a24b2aab8fe7c6f1f154235e1ce, or cef0845b6dcfa2f6c2c832e7f9622551456c741d
Vendor Advisory: https://git.kernel.org/stable/c/0b2c59720e65885a394a017d0cf9cab118914682
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version from your distribution vendor. 2. Reboot system to load new kernel. 3. Verify kernel version after reboot.
🔧 Temporary Workarounds
Disable L2TP functionality
linuxDisable L2TP kernel module to prevent exploitation
modprobe -r l2tp_core
modprobe -r l2tp_eth
modprobe -r l2tp_ip
modprobe -r l2tp_ip6
echo 'blacklist l2tp_core' >> /etc/modprobe.d/blacklist.conf
🧯 If You Can't Patch
- Disable L2TP services and modules if not required
- Implement network segmentation to restrict access to L2TP services
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if L2TP modules are loaded: uname -r && lsmod | grep l2tpCheck Version:
uname -rVerify Fix Applied:
Verify kernel version is patched and L2TP modules are either disabled or patched version is running📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages
- System crash logs
- L2TP connection failures in system logs
Network Indicators:
- Unusual L2TP connection patterns
- Multiple rapid L2TP tunnel establishment attempts
SIEM Query:
source="kernel" AND ("panic" OR "Oops" OR "BUG") AND ("l2tp" OR "tunnel")