# CVE-2026-89806: drm/sysfb: ofdrm: Fix integer overflow in fb_size calculation

> An integer overflow in the Linux kernel's ofdrm driver can cause undefined behavior, potentially leading to a denial of service.

- **Severity:** High 8.4 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Sep 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-101526, BELL-CVE-2026-89806, DEBIAN-CVE-2026-89806, GHSA-2f2m-wrrx-qjxp, UBUNTU-CVE-2026-89806

## What is CVE-2026-89806?

CVE-2026-89806 is a high-severity 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/sysfb: ofdrm: Fix integer overflow in fb_size calculation

The framebuffer size calculation `fb_size = linebytes * height` can
overflow when both values are large (e.g., 46341 * 46341 > INT_MAX).
Since linebytes and height are both int types, the multiplication is
performed as int * int, which results in undefined behavior on overflow.

Use check_mul_overflow() to detect and prevent this overflow, consistent
with the approach used in simpledrm.c and corebootdrm.c.

## Which versions are affected by CVE-2026-89806?


## How do I fix CVE-2026-89806?

Apply the vendor's patch.

## Is CVE-2026-89806 being exploited?

There is no known exploitation of CVE-2026-89806 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89806 and fix it if it is affected.

What it is: CVE-2026-89806 is a high-severity 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-2026-89806 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-2026-89806/ (Markdown: https://insights.sbomify.com/CVE-2026-89806/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89806
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89806
- OSV: https://osv.dev/vulnerability/CVE-2026-89806

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89806/
Summaries are generated and may contain mistakes; the official description above is the record.