# CVE-2026-89819: drm/amd/display: validate plane degamma LUT size for private color prop

> A missing size validation in the AMD display driver allows a local attacker to cause a kernel crash via divide-by-zero or out-of-bounds read.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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:** 16 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-89819, DEBIAN-CVE-2026-89819, GHSA-g935-chxq-f255, UBUNTU-CVE-2026-89819

## What is CVE-2026-89819?

CVE-2026-89819 is a high-severity denial of service vulnerability in Linux, published on 16 Sep 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: validate plane degamma LUT size for private color prop

Unlike the CRTC degamma path, which is guarded by
amdgpu_dm_verify_lut_sizes(), the per-plane degamma LUT size was never
validated before use. __set_dm_plane_degamma() passed the user-supplied
size straight into __is_lut_linear() and, for a non-linear LUT, into
__set_input_tf() -> __drm_lut_to_dc_gamma(), the latter always iterating
MAX_COLOR_LUT_ENTRIES entries regardless of the actual LUT size.

A malformed AMD_PLANE_DEGAMMA_LUT blob (e.g. a single entry) could thus
trigger a divide-by-zero in __is_lut_linear() or an out-of-bounds read in
__drm_lut_to_dc_gamma(). Reject any plane degamma LUT whose size does not
match MAX_COLOR_LUT_ENTRIES, mirroring the invariant the code already
asserts a few lines below (and which the CRTC path enforces).

The AMD_PLANE_DEGAMMA_LUT property is only exposed on builds with
AMD_PRIVATE_COLOR defined.

## Which versions are affected by CVE-2026-89819?


## How do I fix CVE-2026-89819?

Apply the vendor's patch.

## Is CVE-2026-89819 being exploited?

There is no known exploitation of CVE-2026-89819 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89819 and fix it if it is affected.

What it is: CVE-2026-89819 is a high-severity denial of service vulnerability in Linux, published on 16 Sep 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-2026-89819 in the wild and no public exploit code.

Affected product: Linux. 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-2026-89819/ (Markdown: https://insights.sbomify.com/CVE-2026-89819/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89819
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89819
- OSV: https://osv.dev/vulnerability/CVE-2026-89819

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89819/
Summaries are generated and may contain mistakes; the official description above is the record.