CVE-2023-53240
📋 TL;DR
A race condition in the Linux kernel's AF_XDP socket implementation allows a NULL pointer dereference when transmitting packets via sendmsg() on a network interface that isn't fully up. This causes a kernel panic and system crash, affecting systems using AF_XDP sockets for high-performance packet processing.
💻 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 →⚠️ Risk & Real-World Impact
Worst Case
Kernel panic leading to complete system crash and denial of service, requiring physical or remote reboot.
Likely Case
System crash when AF_XDP applications attempt to transmit on interfaces that are down or in transitional states.
If Mitigated
No impact if AF_XDP sockets aren't used or interfaces are properly managed.
🎯 Exploit Status
Requires local access and ability to create AF_XDP sockets. Timing-dependent race condition.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions with commits 1596dae2f17ec5c6e8c8f0e3fec78c5ae55c1e0b, cecc68559cd57fffb2be50685f262b9af2318e16, or ffe19750e68d0bb21e8110b398346eef20b156a7
Vendor Advisory: https://git.kernel.org/stable/c/1596dae2f17ec5c6e8c8f0e3fec78c5ae55c1e0b
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version from your distribution. 2. Reboot system to load new kernel. 3. Verify kernel version with 'uname -r'.
🔧 Temporary Workarounds
Disable AF_XDP socket usage
allPrevent creation of AF_XDP sockets by removing CAP_NET_RAW from non-essential processes or using kernel module blacklisting.
# Remove CAP_NET_RAW capability from processes
# setcap -r CAP_NET_RAW /path/to/application
# Or use kernel module parameters if AF_XDP is modular
🧯 If You Can't Patch
- Restrict AF_XDP socket creation to trusted processes only using capabilities or namespaces.
- Ensure network interfaces are properly managed and avoid bringing interfaces up/down while AF_XDP sockets are active.
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if AF_XDP is in use: 'uname -r' and 'lsmod | grep -i xdp' or check for AF_XDP socket applications.Check Version:
uname -rVerify Fix Applied:
Verify kernel version is patched: 'uname -r' should show version containing the fix commits. Check kernel changelog for commit IDs.📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages with NULL pointer dereference at xsk_sendmsg+0xde
- System crashes when using AF_XDP applications
- dmesg showing 'BUG: kernel NULL pointer dereference' in xsk context
Network Indicators:
- Sudden loss of AF_XDP socket functionality
- Application crashes when transmitting packets
SIEM Query:
source="kernel" AND "NULL pointer dereference" AND "xsk"