# CVE-2026-23012: mm/damon/core: remove call_control in inactive contexts

> A use-after-free in the Linux kernel DAMON subsystem allows local attackers with sysfs write permissions to potentially execute code or escalate privileges.

- **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:** 25 Jan 2026
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2026-23012, DEBIAN-CVE-2026-23012, GHSA-mprh-g3xh-wh7r, UBUNTU-CVE-2026-23012

## What is CVE-2026-23012?

CVE-2026-23012 is a high-severity use after free vulnerability in Linux kernel, published on 25 Jan 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:

mm/damon/core: remove call_control in inactive contexts

If damon_call() is executed against a DAMON context that is not running,
the function returns error while keeping the damon_call_control object
linked to the context's call_controls list.  Let's suppose the object is
deallocated after the damon_call(), and yet another damon_call() is
executed against the same context.  The function tries to add the new
damon_call_control object to the call_controls list, which still has the
pointer to the previous damon_call_control object, which is deallocated. 
As a result, use-after-free happens.

This can actually be triggered using the DAMON sysfs interface.  It is not
easily exploitable since it requires the sysfs write permission and making
a definitely weird file writes, though.  Please refer to the report for
more details about the issue reproduction steps.

Fix the issue by making two changes.  Firstly, move the final
kdamond_call() for cancelling all existing damon_call() requests from
terminating DAMON context to be done before the ctx->kdamond reset.  This
makes any code that sees NULL ctx->kdamond can safely assume the context
may not access damon_call() requests anymore.  Secondly, let damon_call()
to cleanup the damon_call_control objects that were added to the
already-terminated DAMON context, before returning the error.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-23012?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-23012?

Apply the vendor's patch.

## Is CVE-2026-23012 being exploited?

There is no known exploitation of CVE-2026-23012 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-2026-23012 and fix it if it is affected.

What it is: CVE-2026-23012 is a high-severity use after free vulnerability in Linux kernel, published on 25 Jan 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-2026-23012 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-2026-23012/ (Markdown: https://insights.sbomify.com/CVE-2026-23012/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-23012
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-23012
- OSV: https://osv.dev/vulnerability/CVE-2026-23012

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-23012/
Summaries are generated and may contain mistakes; the official description above is the record.