CVE-2025-39901
📋 TL;DR
This CVE describes a vulnerability in the Linux kernel's i40e network driver where debugfs files have insecure read handlers that could allow reading arbitrary kernel memory. The vulnerability affects systems using the i40e driver for Intel Ethernet network adapters. Attackers with local access could potentially exploit this to leak sensitive kernel data.
💻 Affected Systems
- Linux kernel with i40e 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
Local attacker reads arbitrary kernel memory, potentially exposing sensitive information like encryption keys, passwords, or other privileged data.
Likely Case
Information disclosure through reading kernel memory, though exploitation requires careful crafting of inputs and local access.
If Mitigated
No impact if debugfs is disabled or access is restricted to privileged users only.
🎯 Exploit Status
Exploitation requires local access and careful input crafting to trigger the buffer overflow condition in snprintf.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions containing commits 70d3dad7d5ad077965d7a63eed1942b7ba49bfb4, 7d190963b80f4cd99d7008615600aa7cc993c6ba, or 9fcdb1c3c4ba134434694c001dbff343f1ffa319
Vendor Advisory: https://git.kernel.org/stable/c/70d3dad7d5ad077965d7a63eed1942b7ba49bfb4
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version. 2. Reboot system to load new kernel. 3. Verify i40e driver version is updated.
🔧 Temporary Workarounds
Disable debugfs access
linuxRemove debugfs mount or restrict access to prevent exploitation
umount /sys/kernel/debug
chmod 700 /sys/kernel/debug
mount -o remount,noexec,nosuid,nodev /sys/kernel/debug
Restrict debugfs permissions
linuxLimit debugfs access to root only
chown root:root /sys/kernel/debug
chmod 700 /sys/kernel/debug
🧯 If You Can't Patch
- Unmount debugfs filesystem if not needed for debugging
- Implement strict access controls to limit who can access debugfs
🔍 How to Verify
Check if Vulnerable:
Check if debugfs is mounted and accessible, and verify kernel version is before the fix commitsCheck Version:
uname -rVerify Fix Applied:
Verify kernel version includes the fix commits and test that debugfs read operations on i40e files no longer work📡 Detection & Monitoring
Log Indicators:
- Failed read attempts on /sys/kernel/debug/i40e/* files
- Kernel oops or warnings related to i40e driver
Network Indicators:
- None - this is a local vulnerability
SIEM Query:
process.name="cat" AND file.path="/sys/kernel/debug/i40e/*" AND user.id!=0