CVE-2025-39676 – This CVE describes a NULL pointer dereference v... (How to Fix)

Q: What is the severity of CVE-2025-39676?

CVE-2025-39676 has a CVSS score of 5.5 (MEDIUM). This CVE describes a NULL pointer dereference vulnerability in the Linux kernel's qla4xxx SCSI driver. The vulnerability occurs when error pointers are incorrectly propagated instead of NULL values, potentially causing kernel crashes (Oops). Systems running affected Linux kernel versions with qla4xxx driver loaded are at risk.

📋 TL;DR

This CVE describes a NULL pointer dereference vulnerability in the Linux kernel's qla4xxx SCSI driver. The vulnerability occurs when error pointers are incorrectly propagated instead of NULL values, potentially causing kernel crashes (Oops). Systems running affected Linux kernel versions with qla4xxx driver loaded are at risk.

💻 Affected Systems

Products:

Linux kernel with qla4xxx SCSI driver

Versions: Specific kernel versions containing the vulnerable code (check git commits for exact ranges)

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ✅ No

Notes: Only vulnerable if qla4xxx driver is loaded and used. Many systems may not have this driver loaded by default.

📦 What is this software?

Debian Linux by Debian

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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...

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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...

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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...

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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...

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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...

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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...

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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...

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⚠️ Risk & Real-World Impact

🔴

Worst Case

Kernel panic leading to system crash and denial of service, potentially causing data loss or system instability.

🟠

Likely Case

Kernel Oops (crash) resulting in system instability or denial of service, requiring system reboot.

🟢

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 specific SCSI operations.

🏢 Internal Only: MEDIUM - Local users or processes with appropriate privileges could trigger the vulnerability.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Requires ability to trigger specific SCSI operations through the qla4xxx driver. Likely requires local access or specific hardware configuration.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Kernel versions containing the fix commits (325bf7d57c4e2a341e381c5805e454fb69dd78c3 and related)

Vendor Advisory: https://git.kernel.org/stable/c/325bf7d57c4e2a341e381c5805e454fb69dd78c3

Restart Required: Yes

Instructions:

1. Update Linux kernel to version containing the fix commits. 2. Reboot system to load patched kernel. 3. Verify qla4xxx driver is using patched code.

🔧 Temporary Workarounds

Unload qla4xxx driver

Linux

Prevent vulnerability by unloading the vulnerable driver module if not required

sudo rmmod qla4xxx

Blacklist qla4xxx driver

Linux

Prevent driver from loading at boot

echo 'blacklist qla4xxx' | sudo tee /etc/modprobe.d/blacklist-qla4xxx.conf

🧯 If You Can't Patch

Unload qla4xxx driver if not required for system functionality
Restrict access to systems to prevent local exploitation

🔍 How to Verify

Check if Vulnerable:

Check if qla4xxx driver is loaded: lsmod | grep qla4xxx. If loaded, check kernel version against affected ranges.

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version includes fix commits and qla4xxx driver loads without errors.

📡 Detection & Monitoring

Log Indicators:

Kernel Oops messages in /var/log/kern.log or dmesg
System crash/panic logs
SCSI error messages related to qla4xxx

Network Indicators:

None - local vulnerability

SIEM Query:

Search for 'Oops' or 'kernel panic' in system logs with process context involving qla4xxx or SCSI operations

📊 Metadata

CVE ID: CVE-2025-39676

CVSS v3 Score: 5.5 (MEDIUM)

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

CWE: CWE-476

EPSS Score: 0.01% exploit probability (2.3th percentile)

Published: September 5, 2025

Last Updated: January 7, 2026

🔗 References

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