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This security advisory addresses a critical vulnerability found within the Microsoft.WindowsDesktop.App.Runtime component, specifically impacting WPF applications processing XML Paper Specification (XPS) files. When an application attempts to render malicious or specially crafted XPS content, attacker-controlled glyph coordinates can manipulate pointer calculations during destination rendering. This flaw triggers an integer overflow or wraparound condition inside the CD3DGlyphBank::RectFillAlpha function. Consequently, the incorrect pointer arithmetic leads directly to an out-of-bounds write vulnerability in memory. Exploitation of this flaw can result in unexpected application crashes causing process termination, or potentially facilitate more severe memory corruption risks that impact system stability and integrity if proper boundary validations and safety checks are bypassed during graphical processing operations.
DailyCVE Form:
Platform: Windows Desktop Runtime
Version: .NET 8.0, 9.0, 10.0
Vulnerability : Out-of-Bounds Write
Severity: High
date: 10/13/2026
Prediction: 10/13/2026
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The vulnerability stems from improper arithmetic validation within CD3DGlyphBank::RectFillAlpha when parsing XPS glyph coordinates. Attackers craft malicious document structures containing oversized coordinate values designed to trigger integer overflows (CWE-190). When the library computes target memory locations for alpha rectangle fills, the wrapped arithmetic bypasses allocation bounds, causing a memory write operation outside the permitted buffer limits.
bash commands and codes related to the blog
dotnet --info dotnet add package Microsoft.WindowsDesktop.App.Runtime --version 8.0.32 dotnet publish -c Release --self-contained true
how Exploit: (Educational Purposes!)
An attacker constructs a malformed XPS file containing manipulated glyph sequence definitions with extreme coordinate parameters. When a vulnerable Windows Presentation Foundation (WPF) desktop application parses and renders the file using the affected runtime libraries, the internal graphic handler executes `CD3DGlyphBank::RectFillAlpha` with the untrusted coordinates. The resulting integer overflow causes calculation of an invalid memory destination pointer, allowing arbitrary out-of-bounds data writing which terminates the process or corrupts adjacent heap structures.
Protection: from this CVE
To protect systems and applications against this vulnerability, developers and administrators must immediately update their environments to use the latest patched .NET runtime versions. For .NET 8.0 upgrade to version 8.0.32, for .NET 9.0 upgrade to 9.0.21, and for .NET 10.0 upgrade to 10.0.13. Applications utilizing self-contained deployments must be fully recompiled using the updated SDK packages and redeployed to production servers and client endpoints.
Impact:
Successful exploitation of this out-of-bounds write vulnerability can lead to immediate application crashes resulting in denial of service via process termination. Furthermore, depending on heap layout conditions during the out-of-bounds memory write operation, it may introduce vectors for arbitrary code execution or privilege escalation within the context of the running user.
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Sources:
Reported By: github.com
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