CVE-2025-38570
📋 TL;DR
A use-after-free vulnerability in the Linux kernel's fbnic driver allows attackers to potentially crash systems or execute arbitrary code when AF_XDP functionality is used. This affects Linux systems with the fbnic driver loaded, particularly those using specific network configurations.
💻 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 →⚠️ Risk & Real-World Impact
Worst Case
Kernel panic leading to system crash or potential arbitrary code execution with kernel privileges, resulting in complete system compromise.
Likely Case
System crash or instability when AF_XDP functionality is triggered on affected systems, causing denial of service.
If Mitigated
No impact if fbnic driver is not loaded or AF_XDP is not configured/used.
🎯 Exploit Status
Requires local access or ability to trigger AF_XDP functionality. Discovered through CI testing, not known to be actively exploited.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions with commits 21d3f8441c7f317b93ba6a8029610c8b7e3773db, 4b31bcb025cb497da2b01f87173108ff32d350d2, or 4b59f9deff3bdb52b223c85048f1d2924803b817 applied
Vendor Advisory: https://git.kernel.org/stable/c/21d3f8441c7f317b93ba6a8029610c8b7e3773db
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 after reboot.
🔧 Temporary Workarounds
Disable fbnic driver
linuxPrevent loading of vulnerable fbnic driver module
echo 'blacklist fbnic' >> /etc/modprobe.d/blacklist-fbnic.conf
rmmod fbnic
Disable AF_XDP functionality
linuxPrevent use of AF_XDP which triggers the vulnerability
sysctl -w net.core.xdp_disabled=1
🧯 If You Can't Patch
- Ensure fbnic driver is not loaded (check with lsmod | grep fbnic)
- Restrict local user access to systems with fbnic driver loaded
🔍 How to Verify
Check if Vulnerable:
Check if fbnic driver is loaded: lsmod | grep fbnic. If loaded and kernel version is unpatched, system is vulnerable.Check Version:
uname -rVerify Fix Applied:
Check kernel version includes fix commits or is newer than vulnerable versions. Verify fbnic driver functions normally after patch.📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- Oops messages related to fbnic or AF_XDP
- System crash reports
Network Indicators:
- Unusual AF_XDP socket activity
- Network interface errors with fbnic
SIEM Query:
event.category:kernel AND (fbnic OR AF_XDP) AND (panic OR oops OR crash)