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.
- 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
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.
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 | 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.