# CVE-2026-72025: s390/monwriter: Reject buffer reuse with different data length

> A local attacker with access to the monwriter device can trigger memory corruption by changing data lengths, potentially leading to privilege escalation.

- **Severity:** Not scored
- **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:** 15 Aug 2026
- **Updated:** 18 Aug 2026
- **Also known as:** BELL-CVE-2026-72025, DEBIAN-CVE-2026-72025, GHSA-p5g5-p29w-rcw3, UBUNTU-CVE-2026-72025

## What is CVE-2026-72025?

CVE-2026-72025 is a memory corruption vulnerability in Linux, published on 15 Aug 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:

s390/monwriter: Reject buffer reuse with different data length

When data buffers are reused, e.g. for interval sample records, the
first record determines the data length, and the size of the buffer for
user copy. Current monwriter code does not check if the data length was
changed for subsequent records, which also would never happen for valid
user programs.

However, a malicious user could change the data length, resulting in out
of bounds user copy to the kernel buffer, and memory corruption. By
default, the monwriter misc device is created with root-only permissions,
so practical impact is typically low.

Fix this by checking for changed data length and rejecting such records.

## Which versions are affected by CVE-2026-72025?


## How do I fix CVE-2026-72025?

Apply the vendor's patch.

## Is CVE-2026-72025 being exploited?

There is no known exploitation of CVE-2026-72025 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72025 and fix it if it is affected.

What it is: CVE-2026-72025 is a memory corruption vulnerability in Linux, published on 15 Aug 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-2026-72025 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-2026-72025/ (Markdown: https://insights.sbomify.com/CVE-2026-72025/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72025
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72025
- OSV: https://osv.dev/vulnerability/CVE-2026-72025

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72025/
Summaries are generated and may contain mistakes; the official description above is the record.