CVE-2023-53513
📋 TL;DR
This CVE-2023-53513 is an integer overflow vulnerability in the Linux kernel's NBD (Network Block Device) driver. It allows local attackers to trigger undefined behavior through unvalidated ioctl arguments, potentially leading to kernel crashes or other instability. Systems using NBD functionality 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 →⚠️ Risk & Real-World Impact
Worst Case
Kernel panic leading to system crash and denial of service, potentially allowing local privilege escalation if combined with other vulnerabilities.
Likely Case
System instability, kernel crashes, or denial of service affecting NBD functionality.
If Mitigated
Minimal impact if NBD is not used or proper input validation is in place.
🎯 Exploit Status
Requires local access and ability to make specific ioctl calls to NBD devices. The vulnerability was discovered through fuzzing and UBSAN warnings.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions containing commits: 52851d0c3354b397c11d31dfeb8b2a2fc85a0002, 55793ea54d77719a071b1ccc05a05056e3b5e009, fab766c8a1aff715bce7075aab40e780266f8e1a, ffb75ffaa68723276365d0f9d00b03362b750657
Vendor Advisory: https://git.kernel.org/stable/c/52851d0c3354b397c11d31dfeb8b2a2fc85a0002
Restart Required: Yes
Instructions:
1. Update Linux kernel to version containing the fix commits. 2. Check your distribution's security advisories for specific patched kernel versions. 3. Reboot system after kernel update.
🔧 Temporary Workarounds
Disable NBD module
linuxPrevent loading of NBD kernel module if not needed
echo 'blacklist nbd' > /etc/modprobe.d/blacklist-nbd.conf
rmmod nbd
Restrict NBD device access
linuxLimit access to NBD devices to trusted users only
chmod 600 /dev/nbd*
chown root:root /dev/nbd*
🧯 If You Can't Patch
- Disable NBD functionality completely if not required
- Implement strict access controls to limit who can access NBD devices
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if NBD module is loaded: uname -r && lsmod | grep nbdCheck Version:
uname -rVerify Fix Applied:
Verify kernel version is patched and test with known triggering inputs if possible📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- UBSAN warnings about integer overflow
- System crashes related to NBD operations
Network Indicators:
- Unusual NBD traffic patterns if exploited
SIEM Query:
kernel: "UBSAN: Undefined behaviour in fs/buffer.c" OR kernel: "nbd_ioctl" AND (panic OR crash)