.NET WPF CVE-2026-70035

Exploitation requires a WPF-based .NET application that loads or renders attacker-supplied XAML or XPS content, and a user must open/process that malicious document (CVSS UI:R) - there is no server-side, zero-click remote path in default configurations. The vulnerable component is Microsoft.WindowsDesktop.App.Runtime (WPF) on Windows across .NET 8.0 (<8.0.32), 9.0 (<9.0.21), 10.0 (<10.0.13), 11.0 (<11.0.0-rc.2), and .NET Framework 3.5/4.6.2-4.8.1, as well as Visual Studio 2022 17.14 (<17.14.42) and 2026 18.10 (<18.10.4). Limiting factors: required user interaction, the need for an application that consumes untrusted XAML/XPS, and Windows-only exposure; organizations that do not process untrusted markup in WPF apps face substantially lower practical risk.

Signals are moderately strong but not uniformly alarming. The CVSS 3.1 score of 8.8 (AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H) reflects a network-reachable, low-complexity, unauthenticated flaw with total CIA impact - but the UI:R metric is decisive: exploitation requires a user to open or process attacker-controlled content, which is why CISA's SSVC framework rates Automatable=no despite Technical Impact=total. SSVC Exploitation is 'none' (no observed in-the-wild activity), yet publicly available exploit code exists (referenced gist), so POC availability and active exploitation are distinct here and must not be conflated. There is no CISA KEV listing and no EPSS score was provided, so exploitation probability cannot be quantified from the input. Net: this is a genuine priority for organizations running WPF/.NET desktop applications that ingest untrusted XAML/XPS documents, but the UI:R requirement and non-automatable nature make it closer to a targeted/social-engineering RCE than a wormable remote exploit. Note a labeling nuance: the NVD description says '.NET Framework,' but the authoritative dotnet/wpf GHSA advisory scopes the root cause to Microsoft.WindowsDesktop.App.Runtime (WPF) XAML/XPS handling across .NET 8/9/10/11 and .NET Framework - the practical attack surface is WPF document/markup processing, not arbitrary .NET code.

An attacker crafts a malicious XAML or XPS document that abuses unsafe URI fetching/navigation or deeply nested markup and delivers it to a victim via email, download, or a link. When the victim opens it in a vulnerable WPF application, unsafe deserialization of the untrusted markup triggers remote code execution in the context of the user. Public proof-of-concept exploit code is referenced in the intelligence sources.