# CVE-2026-89748: tracing: Fix retry exhaustion in simple ring buffer reader swap

> A logic error in the Linux kernel tracing ring buffer reader swap can cause data corruption and denial of service due to incorrect retry counter handling.

- **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-2026-89748, GHSA-r5q3-2xvw-rm37, UBUNTU-CVE-2026-89748

## What is CVE-2026-89748?

CVE-2026-89748 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:

tracing: Fix retry exhaustion in simple ring buffer reader swap

simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
post-decrements it only after a failed link replacement. On the final
attempt, a successful replacement leaves retry at zero, while a failed
replacement leaves it at -1.

The current !retry test reverses both outcomes. It returns an error after
a successful final replacement, leaving the link update complete but the
reader bookkeeping unfinished. After a failed final replacement, it
falls through and updates the head and reader pointers as though the
replacement succeeded, which can corrupt the ring.

Treat only a negative counter as exhaustion and return the documented
-EBUSY error.

## Which versions are affected by CVE-2026-89748?


## How do I fix CVE-2026-89748?

Apply the vendor's patch.

## Is CVE-2026-89748 being exploited?

There is no known exploitation of CVE-2026-89748 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89748 and fix it if it is affected.

What it is: CVE-2026-89748 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-2026-89748 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-2026-89748/ (Markdown: https://insights.sbomify.com/CVE-2026-89748/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89748
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89748
- OSV: https://osv.dev/vulnerability/CVE-2026-89748

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89748/
Summaries are generated and may contain mistakes; the official description above is the record.