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

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

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **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:** Yes
- **Published:** 6 May 2026
- **Updated:** 21 Oct 2026
- **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, ROOT-OS-DEBIAN-13-CVE-2026-43191, ROOT-OS-UBUNTU-2204-CVE-2026-43191, ROOT-OS-UBUNTU-2404-CVE-2026-43191, UBUNTU-CVE-2026-43191

## 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: Linux kernel.

## How do I fix CVE-2026-43191?

Apply the vendor's patch.

## Is CVE-2026-43191 being exploited?

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

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-43191 and fix it if it is affected.

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

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-43191/ (Markdown: https://insights.sbomify.com/CVE-2026-43191/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-43191
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-43191
- OSV: https://osv.dev/vulnerability/CVE-2026-43191

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-43191/
Summaries are generated and may contain mistakes; the official description above is the record.