CVE-2025-39675

What it actually does

Missing null pointer check in mod_hdcp_hdcp1_create_session() allows dereference of null return value from get_first_active_display() when the display list is empty, causing a kernel crash (availability impact).

Why it matters to the business

Local denial-of-service crashes on Linux systems using AMD display hardware; low EPSS and no KEV status indicate limited active exploitation risk but patching is still required to maintain system stability across the kernel ecosystem.

How an attack unfolds

An attacker with local user privileges triggers HDCP session creation in the AMD display driver under conditions with no active displays present, leading to the unchecked null pointer and subsequent crash.

How to fix it

Update the Linux kernel to include the null pointer check (cherry-picked from commit 5e43eb3cd731); for the listed Maven package apply com.liferay.portal:com.liferay.portal.kernel version 130.0.1 or later.

How to confirm the fix worked

Inspect the mod_hdcp_hdcp1_create_session() function for the added null check on get_first_active_display() and confirm the MOD_HDCP_STATUS_DISPLAY_NOT_FOUND return path; test with empty display list scenarios.

Typical attack path

1. Gain local access to a Linux system with AMD display hardware
2. Trigger mod_hdcp_hdcp1_create_session() when get_first_active_display() returns null
3. Induce null pointer dereference resulting in kernel panic

How to detect it

Review kernel logs for null pointer dereference faults originating from drm/amd/display and mod_hdcp functions; correlate with HDCP session creation attempts on systems lacking active displays.

What your security team should do

• Apply kernel updates containing the referenced commit on all AMD-based systems
• Upgrade com.liferay.portal:com.liferay.portal.kernel to 130.0.1 where deployed
• Monitor kernel logs for display-related oops entries