# CVE-2026-89500: ring-buffer: Make cpu_buffer::free_page a buffer_data_read_page

> A race condition in the Linux kernel ring buffer can cause crashes or memory leaks due to mismatched page orders during resize operations.

- **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:** 11 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-89500, DEBIAN-CVE-2026-89500, GHSA-h78f-r23h-v8hg, UBUNTU-CVE-2026-89500

## What is CVE-2026-89500?

CVE-2026-89500 is a high-severity memory corruption vulnerability in Linux, published on 11 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:

ring-buffer: Make cpu_buffer::free_page a buffer_data_read_page

Discarding a cached reader page after a concurrent ring buffer resize
uses the new global subbuf_order for the free_pages() call. This
mismatched order may crashes the kernel or leaks memory because the cached
page was allocated under the old size.

Save the actual free_page order alongside the page address to ensure we
always refer to the correct value and do not rely on the potentially
stalled cpu_buffer->subbuf_order value. The simplest is to make
free_page a buffer_data_read_page which already covers exactly what we
need: a page address and a page order.

## Which versions are affected by CVE-2026-89500?


## How do I fix CVE-2026-89500?

Apply the vendor's patch.

## Is CVE-2026-89500 being exploited?

There is no known exploitation of CVE-2026-89500 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89500 and fix it if it is affected.

What it is: CVE-2026-89500 is a high-severity memory corruption vulnerability in Linux, published on 11 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-2026-89500 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-2026-89500/ (Markdown: https://insights.sbomify.com/CVE-2026-89500/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89500
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89500
- OSV: https://osv.dev/vulnerability/CVE-2026-89500

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89500/
Summaries are generated and may contain mistakes; the official description above is the record.