# CVE-2023-54172: x86/hyperv: Disable IBT when hypercall page lacks ENDBR instruction

> Linux kernel panics on Hyper-V VMs with IBT enabled due to missing ENDBR instructions, causing denial of service.

- **Severity:** Not scored
- **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:** 30 Dec 2025
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2023-54172, DEBIAN-CVE-2023-54172, GHSA-3fcf-v62x-cm7w, ROOT-OS-UBUNTU-2204-CVE-2023-54172, UBUNTU-CVE-2023-54172

## What is CVE-2023-54172?

CVE-2023-54172 is a denial of service vulnerability in Linux, published on 30 Dec 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/hyperv: Disable IBT when hypercall page lacks ENDBR instruction

On hardware that supports Indirect Branch Tracking (IBT), Hyper-V VMs
with ConfigVersion 9.3 or later support IBT in the guest. However,
current versions of Hyper-V have a bug in that there's not an ENDBR64
instruction at the beginning of the hypercall page. Since hypercalls are
made with an indirect call to the hypercall page, all hypercall attempts
fail with an exception and Linux panics.

A Hyper-V fix is in progress to add ENDBR64. But guard against the Linux
panic by clearing X86_FEATURE_IBT if the hypercall page doesn't start
with ENDBR. The VM will boot and run without IBT.

If future Linux 32-bit kernels were to support IBT, additional hypercall
page hackery would be needed to make IBT work for such kernels in a
Hyper-V VM.

## Which versions are affected by CVE-2023-54172?


## How do I fix CVE-2023-54172?

Apply the vendor's patch.

## Is CVE-2023-54172 being exploited?

There is no known exploitation of CVE-2023-54172 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-54172 and fix it if it is affected.

What it is: CVE-2023-54172 is a denial of service vulnerability in Linux, published on 30 Dec 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-2023-54172 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-2023-54172/ (Markdown: https://insights.sbomify.com/CVE-2023-54172/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-54172
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-54172
- OSV: https://osv.dev/vulnerability/CVE-2023-54172

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-54172/
Summaries are generated and may contain mistakes; the official description above is the record.