# CVE-2025-38049: x86/resctrl: Fix allocation of cleanest CLOSID on platforms with no monitors

> A NULL pointer dereference in the Linux kernel x86/resctrl subsystem can cause a denial of service when creating control groups on platforms without cache occupancy monitors.

- **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:** 18 Apr 2025
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2025-38049, DEBIAN-CVE-2025-38049, GHSA-3f85-ch4h-849r, UBUNTU-CVE-2025-38049

## What is CVE-2025-38049?

CVE-2025-38049 is a medium-severity vulnerability in Linux kernel, published on 18 Apr 2025. 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:

x86/resctrl: Fix allocation of cleanest CLOSID on platforms with no monitors

Commit

  6eac36bb9eb0 ("x86/resctrl: Allocate the cleanest CLOSID by searching closid_num_dirty_rmid")

added logic that causes resctrl to search for the CLOSID with the fewest dirty
cache lines when creating a new control group, if requested by the arch code.
This depends on the values read from the llc_occupancy counters. The logic is
applicable to architectures where the CLOSID effectively forms part of the
monitoring identifier and so do not allow complete freedom to choose an unused
monitoring identifier for a given CLOSID.

This support missed that some platforms may not have these counters.  This
causes a NULL pointer dereference when creating a new control group as the
array was not allocated by dom_data_init().

As this feature isn't necessary on platforms that don't have cache occupancy
monitors, add this to the check that occurs when a new control group is
allocated.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2025-38049?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2025-38049?

Apply the vendor's patch.

## Is CVE-2025-38049 being exploited?

There is no known exploitation of CVE-2025-38049 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-2025-38049 and fix it if it is affected.

What it is: CVE-2025-38049 is a medium-severity vulnerability in Linux kernel, published on 18 Apr 2025. 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-2025-38049 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-2025-38049/ (Markdown: https://insights.sbomify.com/CVE-2025-38049/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-38049
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-38049
- OSV: https://osv.dev/vulnerability/CVE-2025-38049

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-38049/
Summaries are generated and may contain mistakes; the official description above is the record.