CVE-2026-43191 drm/amd/display: Adjust PHY FSM transition to TX_EN-to-PLL_ON for TMDS on DCN35

Medium 5.5 Published 6 May 2026 Updated 21 Oct 2026

A flaw in the AMD display driver can cause a system hang when disabling TMDS output, leading to denial of service.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Local or same network only
Victim action needed: Not needed
Fix: Available

What is CVE-2026-43191?

CVE-2026-43191 is a medium-severity denial of service vulnerability in Linux kernel, published on 6 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

In the Linux kernel, the following vulnerability has been resolved:

drm/amd/display: Adjust PHY FSM transition to TX_EN-to-PLL_ON for TMDS on DCN35

[Why] A backport of the change made for DCN401 that addresses an issue where we turn off the PHY PLL when disabling TMDS output, which causes the OTG to remain stuck.

The OTG being stuck can lead to a hang in the DCHVM's ability to ACK invalidations when it thinks the HUBP is still on but it's not receiving global sync.

The transition to PLL_ON needs to be atomic as there's no guarantee that the thread isn't pre-empted or is able to complete before the IOMMU watchdog times out.

[How] Backport the implementation from dcn401 back to dcn35.

There's a functional difference in when the eDP output is disabled in dcn401 code so we don't want to utilize it directly.

Which versions are affected by CVE-2026-43191?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-43191?

Apply the vendor's patch.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2026-43191 being exploited?

There is no known exploitation of CVE-2026-43191 in the wild and no public exploit code.

All Linux kernel vulnerabilities

Sources

Also known as AZL-85860, BELL-CVE-2026-43191, DEBIAN-CVE-2026-43191, GHSA-2m7x-2cj2-wg69, ROOT-OS-DEBIAN-11-CVE-2026-43191, ROOT-OS-DEBIAN-12-CVE-2026-43191 and 4 more.