# CVE-2024-45818: Deadlock in x86 HVM standard VGA handling

> A deadlock in Xen hypervisor VGA handling allows guest users to cause a denial of service by triggering specific memory access patterns.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N`)
- **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:** 19 Dec 2024
- **Updated:** 31 Dec 2024
- **Also known as:** ALPINE-CVE-2024-45818, DEBIAN-CVE-2024-45818, GHSA-9ppw-wh7x-2qc9, UBUNTU-CVE-2024-45818

## What is CVE-2024-45818?

CVE-2024-45818 is a medium-severity denial of service vulnerability in Xen Xen, published on 19 Dec 2024. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

The hypervisor contains code to accelerate VGA memory accesses for HVM
guests, when the (virtual) VGA is in "standard" mode.  Locking involved
there has an unusual discipline, leaving a lock acquired past the
return from the function that acquired it.  This behavior results in a
problem when emulating an instruction with two memory accesses, both of
which touch VGA memory (plus some further constraints which aren't
relevant here).  When emulating the 2nd access, the lock that is already
being held would be attempted to be re-acquired, resulting in a
deadlock.

This deadlock was already found when the code was first introduced, but
was analysed incorrectly and the fix was incomplete.  Analysis in light
of the new finding cannot find a way to make the existing locking
discipline work.

In staging, this logic has all been removed because it was discovered
to be accidentally disabled since Xen 4.7.  Therefore, we are fixing the
locking problem by backporting the removal of most of the feature.  Note
that even with the feature disabled, the lock would still be acquired
for any accesses to the VGA MMIO region.

Weakness: CWE-667 (Improper Locking)

## Which versions are affected by CVE-2024-45818?

It affects 1 product.


Products: Xen Xen.

## How do I fix CVE-2024-45818?

Apply the vendor's patch.

## Is CVE-2024-45818 being exploited?

There is no known exploitation of CVE-2024-45818 in the wild and no public exploit code.

## Other vulnerabilities in Xen Xen

- [CVE-2017-10912](https://insights.sbomify.com/CVE-2017-10912/): Privilege escalation in n/a (critical 10.0)
- [CVE-2017-10918](https://insights.sbomify.com/CVE-2017-10918/): Memory corruption in n/a (critical 10.0)
- [CVE-2017-10920](https://insights.sbomify.com/CVE-2017-10920/): Memory corruption in n/a (critical 10.0)
- [CVE-2017-10921](https://insights.sbomify.com/CVE-2017-10921/): Memory corruption in n/a (critical 10.0)
- [CVE-2025-27466](https://insights.sbomify.com/CVE-2025-27466/): Mutiple vulnerabilities in the Viridian interface (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-45818 and fix it if it is affected.

What it is: CVE-2024-45818 is a medium-severity denial of service vulnerability in Xen Xen, published on 19 Dec 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-2024-45818 in the wild and no public exploit code.

Affected product: Xen Xen. 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-2024-45818/ (Markdown: https://insights.sbomify.com/CVE-2024-45818/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-45818
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-45818
- OSV: https://osv.dev/vulnerability/CVE-2024-45818

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-45818/
Summaries are generated and may contain mistakes; the official description above is the record.