# CVE-2023-52597: KVM: s390: fix setting of fpc register

> A race condition in KVM s390 allows host process corruption, potentially enabling privilege escalation or code execution on the host.

- **Severity:** Medium 4.0 (`CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 6 Mar 2024
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2023-52597, DEBIAN-CVE-2023-52597, GHSA-6j3q-64jm-q33g, UBUNTU-CVE-2023-52597

## What is CVE-2023-52597?

CVE-2023-52597 is a medium-severity vulnerability in Debian Debian Linux, published on 6 Mar 2024. 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:

KVM: s390: fix setting of fpc register

kvm_arch_vcpu_ioctl_set_fpu() allows to set the floating point control
(fpc) register of a guest cpu. The new value is tested for validity by
temporarily loading it into the fpc register.

This may lead to corruption of the fpc register of the host process:
if an interrupt happens while the value is temporarily loaded into the fpc
register, and within interrupt context floating point or vector registers
are used, the current fp/vx registers are saved with save_fpu_regs()
assuming they belong to user space and will be loaded into fp/vx registers
when returning to user space.

test_fp_ctl() restores the original user space / host process fpc register
value, however it will be discarded, when returning to user space.

In result the host process will incorrectly continue to run with the value
that was supposed to be used for a guest cpu.

Fix this by simply removing the test. There is another test right before
the SIE context is entered which will handles invalid values.

This results in a change of behaviour: invalid values will now be accepted
instead of that the ioctl fails with -EINVAL. This seems to be acceptable,
given that this interface is most likely not used anymore, and this is in
addition the same behaviour implemented with the memory mapped interface
(replace invalid values with zero) - see sync_regs() in kvm-s390.c.

## Which versions are affected by CVE-2023-52597?

It affects 2 products.


Products: Debian Debian Linux, Linux kernel.

## How do I fix CVE-2023-52597?

Apply the vendor's patch.

## Is CVE-2023-52597 being exploited?

There is no known exploitation of CVE-2023-52597 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-52597 and fix it if it is affected.

What it is: CVE-2023-52597 is a medium-severity vulnerability in Debian Debian Linux, published on 6 Mar 2024. 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-2023-52597 in the wild and no public exploit code.

Affected product: Debian Debian 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-2023-52597/ (Markdown: https://insights.sbomify.com/CVE-2023-52597/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-52597
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-52597
- OSV: https://osv.dev/vulnerability/CVE-2023-52597

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-52597/
Summaries are generated and may contain mistakes; the official description above is the record.