CVE-2025-39944 – A use-after-free vulnerability in the Linux ker... (How to Fix)

Q: What is the severity of CVE-2025-39944?

CVE-2025-39944 has a CVSS score of 7.8 (HIGH). A use-after-free vulnerability in the Linux kernel's octeontx2-pf driver allows attackers to potentially crash the system or execute arbitrary code. This affects systems using Marvell OcteonTX2 network adapters with the vulnerable driver loaded. The vulnerability occurs during device cleanup when delayed work items continue accessing freed memory.

📋 TL;DR

A use-after-free vulnerability in the Linux kernel's octeontx2-pf driver allows attackers to potentially crash the system or execute arbitrary code. This affects systems using Marvell OcteonTX2 network adapters with the vulnerable driver loaded. The vulnerability occurs during device cleanup when delayed work items continue accessing freed memory.

💻 Affected Systems

Products:

Linux kernel with octeontx2-pf driver

Versions: Kernel versions containing the vulnerable code up to the fix

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ✅ No

Notes: Only vulnerable when the octeontx2-pf driver is loaded and active (requires Marvell OcteonTX2 hardware or QEMU simulation).

📦 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...

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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 →

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, or potential arbitrary code execution with kernel privileges resulting in complete system compromise.

🟠

Likely Case

System crash or kernel panic when the vulnerable driver is unloaded, causing service disruption.

🟢

If Mitigated

No impact if the vulnerable driver is not loaded or the system is patched.

🌐 Internet-Facing: LOW - Requires local access or ability to trigger driver unloading.

🏢 Internal Only: MEDIUM - Could be exploited by users with local access to trigger driver operations.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: NO

Unauthenticated Exploit: ✅ No

Complexity: HIGH

Requires local access and ability to trigger driver unloading operations. Race condition makes exploitation timing-sensitive.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Kernel versions with commit 2786879aebf363806a13d41e8d5f99202ddd23d9 or later

Vendor Advisory: https://git.kernel.org/stable/c/2786879aebf363806a13d41e8d5f99202ddd23d9

Restart Required: Yes

Instructions:

1. Update Linux kernel to patched version. 2. Rebuild kernel if compiling from source. 3. Reboot system to load new kernel.

🔧 Temporary Workarounds

Unload octeontx2-pf driver

linux

Remove the vulnerable driver if not needed

sudo rmmod octeontx2-pf

Blacklist driver

linux

Prevent driver from loading at boot

echo 'blacklist octeontx2-pf' | sudo tee /etc/modprobe.d/blacklist-octeontx2.conf
sudo update-initramfs -u

🧯 If You Can't Patch

Ensure only trusted users have local access to systems with vulnerable driver
Monitor for system crashes or kernel panics related to octeontx2-pf operations

🔍 How to Verify

Check if Vulnerable:

Check if octeontx2-pf driver is loaded: lsmod | grep octeontx2-pf

Check Version:

uname -r

Verify Fix Applied:

Check kernel version includes fix commit: uname -r and verify against patched versions

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages
KASAN use-after-free reports in dmesg
System crashes during network driver operations

Network Indicators:

None - local vulnerability only

SIEM Query:

search 'kernel: BUG: KASAN: slab-use-after-free' OR 'kernel: octeontx2-pf' in system logs

📊 Metadata

CVE ID: CVE-2025-39944

CVSS v3 Score: 7.8 (HIGH)

CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CWE: CWE-416

EPSS Score: 0.02% exploit probability (5.5th percentile)

Published: October 4, 2025

Last Updated: January 27, 2026

🔗 References

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