# CVE-2026-89499: ring-buffer: Stop remote reader update when page swap fails

> A race condition in the Linux kernel ring buffer allows a local attacker to cause a denial of service by triggering a page swap failure during high event load.

- **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:** DEBIAN-CVE-2026-89499, GHSA-5hxm-7wcj-79fv, UBUNTU-CVE-2026-89499

## What is CVE-2026-89499?

CVE-2026-89499 is a high-severity 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: Stop remote reader update when page swap fails

The remote swap_reader_page callback can return -EBUSY when the writer
moves the head before the remote catches it, particularly during an event
storm on a small buffer. __rb_get_reader_page_from_remote() currently
warns about that failure but continues with the unchanged reader ID and
rearranges the local page list as though the swap succeeded.

Handle the callback failure as a recoverable error. Report it with
pr_warn_ratelimited() and return NULL. Callers already handle a NULL reader
page as a failed attempt. This avoids splicing the same page as both the
previous and new reader without flooding the log under contention.

## Which versions are affected by CVE-2026-89499?


## How do I fix CVE-2026-89499?

Apply the vendor's patch.

## Is CVE-2026-89499 being exploited?

There is no known exploitation of CVE-2026-89499 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89499 and fix it if it is affected.

What it is: CVE-2026-89499 is a high-severity 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-2026-89499 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-2026-89499/ (Markdown: https://insights.sbomify.com/CVE-2026-89499/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89499
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89499
- OSV: https://osv.dev/vulnerability/CVE-2026-89499

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89499/
Summaries are generated and may contain mistakes; the official description above is the record.