# CVE-2026-99158: ring-buffer: Fix false warning in ring_buffer_map_get_reader()


- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 28 Oct 2026
- **Updated:** 28 Oct 2026
- **Also known as:** BELL-CVE-2026-99158, DEBIAN-CVE-2026-99158, GHSA-vq2v-33jv-5cr9, UBUNTU-CVE-2026-99158

## What is CVE-2026-99158?

CVE-2026-99158 is a vulnerability in Linux, published on 28 Oct 2026. 

### Official description

In the Linux kernel, the following vulnerability has been resolved:

ring-buffer: Fix false warning in ring_buffer_map_get_reader()

The mmap reader can warn when it catches up with a writer that is still
committing events. rb_get_reader_page() returns NULL in this case, but
ring_buffer_map_get_reader() treats that result as an error.

The initial rb_per_cpu_empty() check filters out an empty buffer, but it
does not guarantee that the next reader page has committed data. Writers
do not take reader_lock and can advance commit_page before publishing the
committed length on the new page. rb_get_reader_page() can swap to that
page, catch up with the writer and return NULL.

Handle NULL through the existing no-data exit without warning. Remove the
caller's reader_page == commit_page check as well, since the reader-page
helper already handles that case. The existing metadata update and return
path remain in place.

## Which versions are affected by CVE-2026-99158?


## How do I fix CVE-2026-99158?

Upgrade to a fixed version.

## Is CVE-2026-99158 being exploited?

There is no known exploitation of CVE-2026-99158 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-99158 and fix it if it is affected.

What it is: CVE-2026-99158 is a vulnerability in Linux, published on 28 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-99158 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-2026-99158/ (Markdown: https://insights.sbomify.com/CVE-2026-99158/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-99158
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-99158
- OSV: https://osv.dev/vulnerability/CVE-2026-99158

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-99158/
Summaries are generated and may contain mistakes; the official description above is the record.