# CVE-2023-53438: x86/MCE: Always save CS register on AMD Zen IF Poison errors

> A flaw in the Linux kernel's AMD Zen MCE handling causes unnecessary kernel panics on data poison errors, leading to denial of service.

- **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 Sep 2025
- **Updated:** 11 May 2026
- **Also known as:** AZL-71924, BELL-CVE-2023-53438, DEBIAN-CVE-2023-53438, GHSA-wqhj-q653-q9c9, ROOT-OS-DEBIAN-11-CVE-2023-53438, ROOT-OS-UBUNTU-2204-CVE-2023-53438, UBUNTU-CVE-2023-53438

## What is CVE-2023-53438?

CVE-2023-53438 is a medium-severity denial of service vulnerability in Linux kernel, published on 18 Sep 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/MCE: Always save CS register on AMD Zen IF Poison errors

The Instruction Fetch (IF) units on current AMD Zen-based systems do not
guarantee a synchronous #MC is delivered for poison consumption errors.
Therefore, MCG_STATUS[EIPV|RIPV] will not be set. However, the
microarchitecture does guarantee that the exception is delivered within
the same context. In other words, the exact rIP is not known, but the
context is known to not have changed.

There is no architecturally-defined method to determine this behavior.

The Code Segment (CS) register is always valid on such IF unit poison
errors regardless of the value of MCG_STATUS[EIPV|RIPV].

Add a quirk to save the CS register for poison consumption from the IF
unit banks.

This is needed to properly determine the context of the error.
Otherwise, the severity grading function will assume the context is
IN_KERNEL due to the m->cs value being 0 (the initialized value). This
leads to unnecessary kernel panics on data poison errors due to the
kernel believing the poison consumption occurred in kernel context.

## Which versions are affected by CVE-2023-53438?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2023-53438?

Apply the vendor's patch.

## Is CVE-2023-53438 being exploited?

There is no known exploitation of CVE-2023-53438 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-2023-53438 and fix it if it is affected.

What it is: CVE-2023-53438 is a medium-severity denial of service vulnerability in Linux kernel, published on 18 Sep 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-2023-53438 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-2023-53438/ (Markdown: https://insights.sbomify.com/CVE-2023-53438/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-53438
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-53438
- OSV: https://osv.dev/vulnerability/CVE-2023-53438

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-53438/
Summaries are generated and may contain mistakes; the official description above is the record.