CVE-2023-53680
📋 TL;DR
A Linux kernel vulnerability in NFSD (Network File System Daemon) allows out-of-bounds array access when processing malformed NFSv4 compound operations. This can lead to kernel crashes or potential privilege escalation. Systems running vulnerable Linux kernel versions with NFSD enabled are affected.
💻 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 →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 leading to system crash and denial of service, or potential arbitrary code execution with kernel privileges resulting in complete system compromise.
Likely Case
Kernel crash causing system instability and denial of service, requiring system reboot to restore functionality.
If Mitigated
Minimal impact if NFSD is disabled or proper network segmentation prevents access to NFS services.
🎯 Exploit Status
Exploitation requires sending specially crafted NFSv4 compound operations to the NFSD service. Attacker needs network access to NFS port (typically 2049).
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Multiple stable kernel versions with fixes available. Check specific distribution updates.
Vendor Advisory: https://git.kernel.org/stable/c/50827896c365e0f6c8b55ed56d444dafd87c92c5
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version from your distribution's repositories. 2. Reboot system to load new kernel. 3. Verify nfsd service is running with updated kernel.
🔧 Temporary Workarounds
Disable NFSD service
linuxStop and disable the NFSD service if not required
sudo systemctl stop nfs-server
sudo systemctl disable nfs-server
Block NFS port access
linuxUse firewall rules to block access to NFS port (2049)
sudo iptables -A INPUT -p tcp --dport 2049 -j DROP
sudo iptables -A INPUT -p udp --dport 2049 -j DROP
🧯 If You Can't Patch
- Disable NFSD service immediately if not required
- Implement strict network segmentation to limit NFS access to trusted hosts only
🔍 How to Verify
Check if Vulnerable:
Check if nfsd service is running and kernel version is unpatched: 'systemctl status nfs-server' and 'uname -r'Check Version:
uname -rVerify Fix Applied:
Verify kernel version after update matches patched version and nfsd service functions normally📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs in /var/log/kern.log or dmesg
- NFSD service crashes or abnormal termination
Network Indicators:
- Unusual NFS traffic patterns or malformed NFSv4 requests to port 2049
SIEM Query:
source="kernel" AND ("panic" OR "Oops") OR source="nfsd" AND "error"🔗 References
- https://git.kernel.org/stable/c/50827896c365e0f6c8b55ed56d444dafd87c92c5
- https://git.kernel.org/stable/c/804d8e0a6e54427268790472781e03bc243f4ee3
- https://git.kernel.org/stable/c/a64160124d5a078be0c380b1e8a0bad2d040d3a1
- https://git.kernel.org/stable/c/f352c41fa718482979e7e6b71b4da2b718e381cc
- https://git.kernel.org/stable/c/ffcbcf087581ae68ddc0a21460f7ecd4315bdd0e
