# GHSA-c55g-rp4x-fx84: Microsoft DirectX: .spritefont multiply overflow only in 32-bit builds

> An integer overflow in the DirectX Tool Kit SpriteFont reader allows remote code execution when processing untrusted spritefont files in 32-bit builds.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Not stated
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 18 May 2026

## What is GHSA-c55g-rp4x-fx84?

GHSA-c55g-rp4x-fx84 is a vulnerability in directxtk_desktop_win10, published on 18 May 2026. 

### Official description

### Impact
The spritefont reader can be induced to perform a 32-bit overflow multiply that could in theory result in a RCE.

This impacts the use of the *DirectX Tool Kit* **SpriteFont** class file loading ctor if given untrusted data files.

> Note this only applies to x86/ARM builds of the library. ARM64 and x64 native is not subject to this issue.

### Patches
This bug has been fixed in the May 7, 2026 release. Alternatively, users can update their copy of the reader as per [this commit](https://github.com/microsoft/DirectXTK/commit/ef1bd5d7f492c39dd0cd87493ba8ea38725c9791).

### Workarounds
This does not apply if a project's .spritefont files are all 'trusted' data that were included with an application. It's primarily an issue only if developers are using user-provided or network downloaded spritefont files.

## Which versions are affected by GHSA-c55g-rp4x-fx84?

4 open source packages ship an affected version, including directxtk_desktop_win10 and directxtk_uwp.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `directxtk_desktop_win10` | NuGet | All versions | 2026.5.8.1 |
| `directxtk_desktop_win10` | NuGet | All versions | 2026.5.8.1 |
| `directxtk_uwp` | NuGet | All versions | 2026.5.8.1 |
| `directxtk_uwp` | NuGet | All versions | 2026.5.8.1 |

## How do I fix GHSA-c55g-rp4x-fx84?

Upgrade directxtk_desktop_win10 to 2026.5.8.1 or later.

## Is GHSA-c55g-rp4x-fx84 being exploited?

There is no known exploitation of GHSA-c55g-rp4x-fx84 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for GHSA-c55g-rp4x-fx84 and fix it if it is affected.

What it is: GHSA-c55g-rp4x-fx84 is a vulnerability in directxtk_desktop_win10, published on 18 May 2026. 
Exploitation: There is no known exploitation of GHSA-c55g-rp4x-fx84 in the wild and no public exploit code.

Affected packages and fixed versions:
- directxtk_desktop_win10 (NuGet): affected all versions; fixed in 2026.5.8.1
- directxtk_desktop_win10 (NuGet): affected all versions; fixed in 2026.5.8.1
- directxtk_uwp (NuGet): affected all versions; fixed in 2026.5.8.1
- directxtk_uwp (NuGet): affected all versions; fixed in 2026.5.8.1

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/GHSA-c55g-rp4x-fx84/ (Markdown: https://insights.sbomify.com/GHSA-c55g-rp4x-fx84/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/GHSA-c55g-rp4x-fx84

---
From sbomify Insights: https://insights.sbomify.com/GHSA-c55g-rp4x-fx84/
Summaries are generated and may contain mistakes; the official description above is the record.