# CVE-2026-89749: tracing: Fix crash passing ERR_PTR to kthread_stop()

> A local attacker can trigger a kernel crash by inducing memory pressure during boot-time tracing self-tests, causing a null pointer dereference.

- **Severity:** Not scored
- **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:** 11 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-100491, BELL-CVE-2026-89749, DEBIAN-CVE-2026-89749, GHSA-hwhc-m4xq-f4r2, UBUNTU-CVE-2026-89749

## What is CVE-2026-89749?

CVE-2026-89749 is a 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 crash passing ERR_PTR to kthread_stop()

event_test_stuff() calls kthread_run() and unconditionally passes the
returned task_struct pointer to kthread_stop(). kthread_run() returns an
error pointer such as ERR_PTR(-ENOMEM) when kthread creation fails, for
example under memory pressure during the boot-time event self-test.
kthread_stop() then dereferences the invalid pointer, crashing the kernel.

Check the result of kthread_run() before passing it to kthread_stop(). Use
WARN_ON() so that a failure to create the self-test thread does not go
unnoticed, matching the ring-buffer self-test fix in commit
91542863abad ("ring-buffer: Fix crash passing ERR_PTR to kthread_stop()").

## Which versions are affected by CVE-2026-89749?


## How do I fix CVE-2026-89749?

Apply the vendor's patch.

## Is CVE-2026-89749 being exploited?

There is no known exploitation of CVE-2026-89749 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89749 and fix it if it is affected.

What it is: CVE-2026-89749 is a 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-2026-89749 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-2026-89749/ (Markdown: https://insights.sbomify.com/CVE-2026-89749/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89749
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89749
- OSV: https://osv.dev/vulnerability/CVE-2026-89749

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89749/
Summaries are generated and may contain mistakes; the official description above is the record.