CVE-2025-39875
📋 TL;DR
This CVE describes a NULL pointer dereference vulnerability in the Linux kernel's igb network driver when executing the ethtool loopback test. The vulnerability occurs because test rings lack associated q_vectors, causing a crash when the driver attempts to access invalid memory. Systems using the igb driver with ethtool loopback testing capabilities are affected.
💻 Affected Systems
- Linux kernel with igb driver
📦 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 →⚠️ Risk & Real-World Impact
Worst Case
Kernel panic leading to system crash and denial of service, potentially requiring physical access or remote management to restore functionality.
Likely Case
System crash or kernel panic when an administrator or automated tool runs the ethtool loopback test on affected network interfaces.
If Mitigated
No impact if ethtool loopback testing is not performed on affected interfaces.
🎯 Exploit Status
Exploitation requires local access with ability to execute ethtool commands, typically requiring root or privileged user permissions.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions with commits 473be7d39efd3be383e9c0c8e44b53508b4ffeb5 and 75871a525a596ff4d16c4aebc0018f8d0923c9b1 applied
Vendor Advisory: https://git.kernel.org/stable/c/473be7d39efd3be383e9c0c8e44b53508b4ffeb5
Restart Required: No
Instructions:
1. Update Linux kernel to version containing the fix commits. 2. For distributions: Use package manager to update kernel package. 3. For custom kernels: Apply patches from kernel.org and rebuild.
🔧 Temporary Workarounds
Disable ethtool loopback testing
allPrevent execution of ethtool loopback tests on affected interfaces
# Restrict ethtool access to privileged users only
# Consider removing ethtool from non-admin accounts
🧯 If You Can't Patch
- Restrict ethtool command execution to trusted administrators only
- Implement monitoring for ethtool loopback test execution attempts
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if igb driver is loaded: 'uname -r' and 'lsmod | grep igb'Check Version:
uname -rVerify Fix Applied:
Verify kernel version includes fix commits or test ethtool loopback on igb interface (use with caution)📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- System crash/reboot events
- ethtool command execution in audit logs
Network Indicators:
- Sudden loss of network connectivity on affected interfaces
SIEM Query:
Search for: 'kernel panic' OR 'ethool' OR 'igb driver crash' in system logs