# CVE-2026-46021: thermal: core: Fix thermal zone governor cleanup issues

> A race condition in the Linux kernel thermal subsystem can lead to a use-after-free, potentially allowing code execution or denial of service.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:** 27 May 2026
- **Updated:** 15 Oct 2026
- **Also known as:** AZL-88664, BELL-CVE-2026-46021, DEBIAN-CVE-2026-46021, GHSA-7x76-cw6q-rm95, ROOT-OS-DEBIAN-11-CVE-2026-46021, ROOT-OS-DEBIAN-12-CVE-2026-46021, ROOT-OS-UBUNTU-2204-CVE-2026-46021, ROOT-OS-UBUNTU-2404-CVE-2026-46021, UBUNTU-CVE-2026-46021

## What is CVE-2026-46021?

CVE-2026-46021 is a medium-severity use after free vulnerability in Linux kernel, published on 27 May 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:

thermal: core: Fix thermal zone governor cleanup issues

If thermal_zone_device_register_with_trips() fails after adding
a thermal governor to the thermal zone being registered, the
governor is not removed from it as appropriate which may lead to
a memory leak.

In turn, thermal_zone_device_unregister() calls thermal_set_governor()
without acquiring the thermal zone lock beforehand which may race with
a governor update via sysfs and may lead to a use-after-free in that
case.

Address these issues by adding two thermal_set_governor() calls, one to
thermal_release() to remove the governor from the given thermal zone,
and one to the thermal zone registration error path to cover failures
preceding the thermal zone device registration.

Weakness: CWE-401 (Missing Release of Memory after Effective Lifetime)

## Which versions are affected by CVE-2026-46021?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-46021?

Apply the vendor's patch.

## Is CVE-2026-46021 being exploited?

There is no known exploitation of CVE-2026-46021 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-46021 and fix it if it is affected.

What it is: CVE-2026-46021 is a medium-severity use after free vulnerability in Linux kernel, published on 27 May 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-2026-46021 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2026-46021/ (Markdown: https://insights.sbomify.com/CVE-2026-46021/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-46021
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-46021
- OSV: https://osv.dev/vulnerability/CVE-2026-46021

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-46021/
Summaries are generated and may contain mistakes; the official description above is the record.