CVE-2025-39675 – A null pointer dereference vulnerability in the... (How to Fix)

Q: What is the severity of CVE-2025-39675?

CVE-2025-39675 has a CVSS score of 5.5 (MEDIUM). A null pointer dereference vulnerability in the Linux kernel's AMD display driver could cause kernel crashes or denial of service. This affects systems running vulnerable Linux kernel versions with AMD graphics hardware. The vulnerability occurs when the display list is empty during HDCP session creation.

📋 TL;DR

A null pointer dereference vulnerability in the Linux kernel's AMD display driver could cause kernel crashes or denial of service. This affects systems running vulnerable Linux kernel versions with AMD graphics hardware. The vulnerability occurs when the display list is empty during HDCP session creation.

💻 Affected Systems

Products:

Linux kernel with AMD display driver (drm/amd/display)

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

Operating Systems: Linux distributions with vulnerable kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Requires AMD graphics hardware and the affected display driver module to be loaded. Systems without AMD graphics or with the module disabled are not vulnerable.

📦 What is this software?

Debian Linux by Debian

View all CVEs affecting Debian Linux →

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 and denial of service, potentially requiring physical access to restart the system.

🟠

Likely Case

System instability or crash when attempting to create HDCP sessions with no active displays, requiring reboot to restore functionality.

🟢

If Mitigated

Graceful error handling returns MOD_HDCP_STATUS_DISPLAY_NOT_FOUND instead of crashing.

🌐 Internet-Facing: LOW - Requires local access or ability to trigger specific display driver operations.

🏢 Internal Only: MEDIUM - Local users or processes could trigger the crash, affecting system availability.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploitation requires triggering the specific code path in mod_hdcp_hdcp1_create_session() with an empty display list. This typically requires local access and ability to manipulate display operations.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Kernel versions containing commits 5e43eb3cd731649c4f8b9134f857be62a416c893 or backported fixes

Vendor Advisory: https://git.kernel.org/stable/c/2af45aadb7b5d3852c76e2d1e985289ada6f48bf

Restart Required: Yes

Instructions:

1. Update Linux kernel to patched version from your distribution vendor. 2. Reboot system to load new kernel. 3. Verify kernel version after reboot.

🔧 Temporary Workarounds

Disable AMD display driver module

Linux

Prevent loading of the vulnerable drm/amd/display module

echo 'blacklist amdgpu' >> /etc/modprobe.d/blacklist.conf
update-initramfs -u
reboot

🧯 If You Can't Patch

Restrict local access to prevent untrusted users from triggering the vulnerability
Monitor system logs for kernel panic events and implement automated recovery procedures

🔍 How to Verify

Check if Vulnerable:

Check if running a vulnerable kernel version and if AMD display driver is loaded: 'lsmod | grep amdgpu' and 'uname -r'

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version after update and check that system doesn't crash when attempting HDCP operations with no displays

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages in /var/log/kern.log or dmesg
HDCP-related error messages
System crash/reboot events

Network Indicators:

None - this is a local vulnerability

SIEM Query:

source="kernel" AND ("panic" OR "Oops" OR "NULL pointer dereference") AND "amdgpu" OR "drm/amd/display"

📊 Metadata

CVE ID: CVE-2025-39675

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: 0.02% exploit probability (2.6th percentile)

Published: September 5, 2025

Last Updated: January 7, 2026

🔗 References

📤 Share & Export

📄 Export Markdown 📋 Export JSON

🔗 Related Vulnerabilities

If you're affected by CVE-2025-39675, you might also want to check these: