CVE-2023-53200
📋 TL;DR
This CVE describes a memory leak vulnerability in the Linux kernel's netfilter subsystem when creating new network namespaces. If the xt_register_table function fails after allocating percpu counter blocks, the memory isn't properly freed, leading to resource exhaustion over time. This affects Linux systems using netfilter with network namespace functionality.
💻 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 →⚠️ Risk & Real-World Impact
Worst Case
Repeated exploitation could lead to kernel memory exhaustion, causing system instability, denial of service, or kernel panic.
Likely Case
Slow memory leak over extended periods during network namespace creation failures, potentially degrading system performance.
If Mitigated
Minimal impact with proper monitoring and resource limits in place.
🎯 Exploit Status
Exploitation requires local access and CAP_NET_ADMIN capabilities. The leak occurs only when xt_register_table fails (primarily ENOMEM scenarios), making reliable exploitation challenging.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Multiple stable kernel versions with commits: 0af8c09c8968, 3cc9610a87b7, 512b6c4b83c9, e306dbee4c98
Vendor Advisory: https://git.kernel.org/stable/c/0af8c09c896810879387decfba8c942994bb61f5
Restart Required: No
Instructions:
1. Update Linux kernel to patched version from your distribution. 2. For custom kernels, apply the relevant commit from kernel git repository. 3. No reboot required for live patching systems; otherwise kernel reboot needed.
🔧 Temporary Workarounds
Restrict network namespace creation
allLimit ability to create network namespaces to reduce attack surface
sysctl -w kernel.unprivileged_userns_clone=0
capsh --drop=cap_net_admin -- -c 'your_command'
🧯 If You Can't Patch
- Implement strict resource limits (cgroups) to contain memory exhaustion
- Monitor kernel memory usage and alert on unusual patterns
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if netfilter with network namespace support is enabled: 'uname -r' and verify against patched versionsCheck Version:
uname -rVerify Fix Applied:
Verify kernel version includes one of the fix commits: 'grep -i "0af8c09c8968\|3cc9610a87b7\|512b6c4b83c9\|e306dbee4c98" /proc/version'📡 Detection & Monitoring
Log Indicators:
- Kernel oom-killer messages
- System memory exhaustion warnings
- Failed network namespace creation in system logs
Network Indicators:
- Unusual network namespace creation patterns
SIEM Query:
source="kernel" AND ("oom" OR "memory" OR "netns")