CVE-2026-35433 — Microsoft.WindowsDesktop.…
HIGHCVE-2026-35433 is a high-severity (CVSS 7.3) Improper Input Validation vulnerability in Microsoft.WindowsDesktop.App.Runtime.win-arm64. A fix is available for Microsoft.WindowsDesktop.App.Runtime.win-arm64 — see the affected versions and patch details below.
Microsoft Security Advisory CVE-2026-35433 – .NET Elevation of Privilege Vulnerability
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-35433.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-35433 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 380,526 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
Microsoft.WindowsDesktop.App.Runtime.win-arm64.NETMicrosoft.WindowsDesktop.App.Runtime.win-x64.NETMicrosoft.WindowsDesktop.App.Runtime.win-x86.NETMicrosoft.WindowsDesktop.App.Runtime.win-x86.NETMicrosoft.WindowsDesktop.App.Runtime.win-x64.NETMicrosoft.WindowsDesktop.App.Runtime.win-arm64.NETMicrosoft.WindowsDesktop.App.Runtime.win-arm64.NETMicrosoft.WindowsDesktop.App.Runtime.win-x64+1 moreReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects NuGet packages — download data is not available via public APIs for these ecosystems.
Description
Executive Summary:
Microsoft is releasing this security advisory to provide information about a vulnerability in .NET 8.0, .NET 9.0, and .NET 10.0. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability.
Improper input validation in .NET allows an unauthorized attacker to elevate privileges locally.
Announcement
Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/398
CVSS Details
- Version: 3.1
- Severity: High
- Score: 7.3
- Vector: AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L/E:U/RL:O/RC:C
- Weakness: CWE-122: Heap-based Buffer Overflow, CWE-20: Improper Input Validation
Affected Platforms
- Platforms: Windows
- Architectures: All
<a name="affected-packages"></a>Affected Packages
The vulnerability affects any Microsoft .NET project if it uses any of affected package versions listed below
<a name=".NET 10"></a>.NET 10
| Package name | Affected version | Patched version |
|---|---|---|
| Microsoft.WindowsDesktop.App.Runtime.win-arm64 | >= 10.0.0, <= 10.0.7 | 10.0.8 |
| Microsoft.WindowsDesktop.App.Runtime.win-x64 | >= 10.0.0, <= 10.0.7 | 10.0.8 |
| Microsoft.WindowsDesktop.App.Runtime.win-x86 | >= 10.0.0, <= 10.0.7 | 10.0.8 |
<a name=".NET 9"></a>.NET 9
| Package name | Affected version | Patched version |
|---|---|---|
| Microsoft.WindowsDesktop.App.Runtime.win-arm64 | >= 9.0.0, <= 9.0.15 | 9.0.16 |
| MMicrosoft.WindowsDesktop.App.Runtime.win-x64 | >= 9.0.0, <= 9.0.15 | 9.0.16 |
| Microsoft.WindowsDesktop.App.Runtime.win-x86 | >= 9.0.0, <= 9.0.15 | 9.0.16 |
<a name=".NET 8"></a>.NET 8
| Package name | Affected version | Patched version |
|---|---|---|
| Microsoft.WindowsDesktop.App.Runtime.win-arm64 | >= 8.0.0, <= 8.0.26 | 8.0.27 |
| MMicrosoft.WindowsDesktop.App.Runtime.win-x64 | >= 8.0.0, <= 8.0.26 | 8.0.27 |
| Microsoft.WindowsDesktop.App.Runtime.win-x86 | >= 8.0.0, <= 8.0.26 | 8.0.27 |
Advisory FAQ
<a name="how-affected"></a>How do I know if I am affected?
If using a package listed in affected packages, an application is exposed to the vulnerability.
<a name="how-fix"></a>How do I fix the issue?
- To fix the issue please install the latest version of .NET 8.0, NET 9.0, or .NET 10.0, as appropriate. If developers have installed one or more .NET SDKs through Visual Studio, Visual Studio will prompt them to update Visual Studio, which will also update the applications's .NET SDKs.
- If a developer's application references the vulnerable package, update the package reference to the patched version. Developers can list the versions they have installed by running the
dotnet --infocommand.
Once developers have installed the updated runtime or SDK, they can restart the app for the update to take effect.
Additionally, if developers have deployed self-contained applications targeting any of the impacted versions, these applications are also vulnerable and must be recompiled and redeployed.
Other Information
Reporting Security Issues
A potential security issue has been found in a supported version of .NET, please report it to the Microsoft Security Response Center (MSRC) via the MSRC Researcher Portal. Further information can be found in the MSRC Report an Issue FAQ.
Security reports made through MSRC may qualify for the Microsoft .NET Bounty. Details of the Microsoft .NET Bounty Program including terms and conditions are at https://aka.ms/corebounty.
Support
Questions about this issue can be submitted to the .NET GitHub organization. The main repos are located at https://github.com/dotnet/runtime. The Announcements repo (https://github.com/dotnet/Announcements) will contain this bulletin as an issue and will include a link to a discussion issue. Questions should be submitted thorugh the linked discussion issue.
Disclaimer
The information provided in this advisory is provided "as is" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.
External Links
Acknowledgements
Ky0toFu
Revisions
V1.0 (May 12, 2026): Advisory published.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| .NETNuGet | Microsoft.WindowsDesktop.App.Runtime.win-arm64 | ≥ 8.0.0&&< 8.0.27 | 8.0.27dotnet add package Microsoft.WindowsDesktop.App.Runtime.win-arm64 --version 8.0.27 |
| .NETNuGet | Microsoft.WindowsDesktop.App.Runtime.win-x64 | ≥ 8.0.0&&< 8.0.27 | 8.0.27dotnet add package Microsoft.WindowsDesktop.App.Runtime.win-x64 --version 8.0.27 |
| .NETNuGet | Microsoft.WindowsDesktop.App.Runtime.win-x86 | ≥ 8.0.0&&< 8.0.27 | 8.0.27dotnet add package Microsoft.WindowsDesktop.App.Runtime.win-x86 --version 8.0.27 |
| .NETNuGet | Microsoft.WindowsDesktop.App.Runtime.win-x86 | ≥ 9.0.0&&< 9.0.16 | 9.0.16dotnet add package Microsoft.WindowsDesktop.App.Runtime.win-x86 --version 9.0.16 |
| .NETNuGet | Microsoft.WindowsDesktop.App.Runtime.win-x64 | ≥ 9.0.0&&< 9.0.16 | 9.0.16dotnet add package Microsoft.WindowsDesktop.App.Runtime.win-x64 --version 9.0.16 |
| .NETNuGet | Microsoft.WindowsDesktop.App.Runtime.win-arm64 | ≥ 9.0.0&&< 9.0.16 | 9.0.16dotnet add package Microsoft.WindowsDesktop.App.Runtime.win-arm64 --version 9.0.16 |
Affected Products
.netmicrosoft.net frameworkmicrosoftDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Microsoft.WindowsDesktop.App.Runtime.win-arm64, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update Microsoft.WindowsDesktop.App.Runtime.win-arm64 to 8.0.27 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-35433 is resolved across your whole dependency graph.
Workarounds
Stop feeding it untrusted input: reject or quarantine files and payloads from unverified sources until you can upgrade, restrict accepted formats to the ones you actually need, and run the parsing or decoding step in a least-privileged sandbox or short-lived worker so a crash or corrupted read cannot reach the rest of the process.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
As this flaw allows an unauthenticated attacker to elevate privileges locally, it has been rated with an important severity. This vulnerability affects .NET running on Windows systems. Therefore, Red Hat products are not affected by this issue.
Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible.Source: Red Hat security advisory for CVE-2026-35433 (CC BY 4.0)
Frequently Asked Questions
Is CVE-2026-35433 in your dependencies?
Find it across NuGet, including transitive dependencies.