CVE-2025-39937

Q: What is the severity of CVE-2025-39937?

CVE-2025-39937 has a CVSS score of 5.5 (MEDIUM). A NULL pointer dereference vulnerability in the Linux kernel's rfkill-gpio driver could cause kernel crashes on specific x86 systems with BCM4752 or LNV4752 ACPI devices. This affects Linux systems where the driver attempts to read an uninitialized type_name variable when no 'type' property exists. The vulnerability requires local access to trigger.

5.5 MEDIUM

Denial of Service

📋 TL;DR

A NULL pointer dereference vulnerability in the Linux kernel's rfkill-gpio driver could cause kernel crashes on specific x86 systems with BCM4752 or LNV4752 ACPI devices. This affects Linux systems where the driver attempts to read an uninitialized type_name variable when no 'type' property exists. The vulnerability requires local access to trigger.

💻 Affected Systems

Products:

Linux kernel

Versions: Kernel versions between commit 7d5e9737efda and the fix commits

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Only affects x86 systems with BCM4752 or LNV4752 ACPI devices. Most systems won't have this specific hardware.

📦 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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⚠️ Risk & Real-World Impact

🔴

Worst Case

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

🟠

Likely Case

System crash or kernel panic on affected hardware when rfkill-gpio driver binds to specific ACPI devices.

🟢

If Mitigated

No impact if systems don't have the specific ACPI hardware or if the stack happens to contain NULL at the right location.

🌐 Internet-Facing: LOW - Requires local access to trigger, not remotely exploitable.

🏢 Internal Only: MEDIUM - Local users or processes could cause system crashes on affected hardware.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: NO

Unauthenticated Exploit: ✅ No

Complexity: LOW

Exploitation requires local access and specific hardware. The vulnerability is a NULL pointer dereference that's triggered during normal driver initialization.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Fixed in kernel commits: 184f608a68f96794e8fe58cd5535014d53622cde, 21a39b958b4bcf44f7674bfbbe1bbb8cad0d842d, 21ba85d9d508422ca9e6698463ff9357c928c22d, 47ade5f9d70b23a119ec20b1c6504864b2543a79, 689aee35ce671aab752f159e5c8e66d7685e6887

Vendor Advisory: https://git.kernel.org/stable/c/184f608a68f96794e8fe58cd5535014d53622cde

Restart Required: Yes

Instructions:

1. Update to a kernel version containing the fix commits. 2. Reboot the system. 3. Verify the kernel version after reboot.

🔧 Temporary Workarounds

Disable rfkill-gpio module

linux

Prevent loading of the vulnerable driver module

echo 'blacklist rfkill-gpio' >> /etc/modprobe.d/blacklist.conf
rmmod rfkill-gpio

Remove hardware triggering

linux

Disable or remove BCM4752/LNV4752 ACPI devices if present

Check ACPI devices: acpidump | grep -i 'BCM4752\|LNV4752'

🧯 If You Can't Patch

Restrict local access to systems with vulnerable hardware
Monitor system logs for kernel panic events related to rfkill-gpio

🔍 How to Verify

Check if Vulnerable:

Check kernel version and if rfkill-gpio module is loaded on systems with BCM4752/LNV4752 ACPI devices

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version includes fix commits and test rfkill-gpio functionality

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages
rfkill-gpio driver crash logs
NULL pointer dereference in kernel logs

Network Indicators:

None - local vulnerability only

SIEM Query:

source="kernel" AND ("rfkill-gpio" OR "NULL pointer dereference" OR "kernel panic")

📊 Metadata

CVE ID: CVE-2025-39937

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: 0.04% exploit probability (12th percentile)

Published: October 4, 2025

Last Updated: January 27, 2026

📋 TL;DR

💻 Affected Systems

📦 What is this software?

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

⚠️ Risk & Real-World Impact

Worst Case

Likely Case

If Mitigated

🎯 Exploit Status

🛠️ Fix & Mitigation

✅ Official Fix

Instructions:

🔧 Temporary Workarounds

Disable rfkill-gpio module

Remove hardware triggering

🧯 If You Can't Patch

🔍 How to Verify

Check if Vulnerable:

Check Version:

Verify Fix Applied:

📡 Detection & Monitoring

Log Indicators:

Network Indicators:

SIEM Query:

📊 Metadata

🔗 References

📤 Share & Export

🔗 Related Vulnerabilities