# CVE-2026-90270: arm_mpam: Disable driver unbind to avoid UAF

> A local attacker with high privileges can trigger a use-after-free in the Linux kernel MPAM driver by unbinding an MSC, potentially leading to code execution or privilege escalation.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 17 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-90270, GHSA-w5mj-8cp5-g38h, UBUNTU-CVE-2026-90270

## What is CVE-2026-90270?

CVE-2026-90270 is an use after free vulnerability in Linux, published on 17 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:

arm_mpam: Disable driver unbind to avoid UAF

When a user unbinds an MSC and that MSC is the only MSC left for a
component then the corresponding mpam_component will be freed. If the user
then goes on to read the schemata file in the resctrl filesystem then the
mpam_component will be accessed from resctrl_arch_get_config() leading to a
use after free.

As the MPAM driver is not a module the unbind sysfs interface is the only
way to trigger the remove. Instead of dealing with the complexity of
allowing some unused MSC to unbind just remove the unbind sysfs interface.

## Which versions are affected by CVE-2026-90270?


## How do I fix CVE-2026-90270?

Apply the vendor's patch.

## Is CVE-2026-90270 being exploited?

There is no known exploitation of CVE-2026-90270 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90270 and fix it if it is affected.

What it is: CVE-2026-90270 is an use after free vulnerability in Linux, published on 17 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-2026-90270 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-2026-90270/ (Markdown: https://insights.sbomify.com/CVE-2026-90270/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90270
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90270
- OSV: https://osv.dev/vulnerability/CVE-2026-90270

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90270/
Summaries are generated and may contain mistakes; the official description above is the record.