Deserialization flaw in .NET lets unauthenticated attackers run code
Priority MEDIUM 42CWE-502Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- Required
- Attack complexity
- Low
- Impact type
- Code execution
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-502.
Summary
Microsoft .NET 8.0, 9.0, 10.0 and 11.0 runtimes and Visual Studio 2022 version 17.14 and Visual Studio 2026 version 18.10 are affected, along with the matching Microsoft.WindowsDesktop.App.Runtime NuGet packages. Deserialization of untrusted data (CWE-502) lets an unauthenticated remote attacker execute code. The attack needs user interaction.
Written with Claude Haiku 5.5 from the sources below · 2026-10-28
Description from the CNA
Deserialization of untrusted data in .NET allows an unauthorized attacker to execute code over a network.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00843 58th percentileScored 2026-11-08
Fix Fixed .NET 10.0 runtime (Microsoft): 10.0.13.NET 11.0 runtime (Microsoft): 11.0.0-rc.2+7 more productsRed Hat: 1 advisory
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Microsoft | .NET 10.0 runtime | 10.0.0 to before 10.0.13 | 10.0.13 | Patch available | CNA |
| Microsoft | .NET 11.0 runtime | 11.0.0 to before 11.0.0-rc.2 | 11.0.0-rc.2 | Patch available | CNA |
| Microsoft | .NET 8.0 runtime | 8.0.0 to before 8.0.32 | 8.0.32 | Patch available | CNA |
| Microsoft | .NET 9.0 runtime | 9.0.0 to before 9.0.21 | 9.0.21 | Patch available | CNA |
| Microsoft | Microsoft Visual Studio 2022 version 17.14 | 17.14.0 to before 17.14.42 | 17.14.42 | Patch available | CNA |
| Microsoft | Microsoft Visual Studio 2026 version 18.10 | 18.10.0 to before 18.10.4 | 18.10.4 | Patch available | CNA |
| — | Microsoft.WindowsDesktop.App.Runtime.win-arm64 (NuGet) | 9.0.0 to before 9.0.21 | 9.0.21 | Patch available | GHSA-c27m-942f-rcfh |
| — | Microsoft.WindowsDesktop.App.Runtime.win-x64 (NuGet) | 9.0.0 to before 9.0.21 | 9.0.21 | Patch available | GHSA-c27m-942f-rcfh |
| — | Microsoft.WindowsDesktop.App.Runtime.win-x86 (NuGet) | 9.0.0 to before 9.0.21 | 9.0.21 | Patch available | GHSA-c27m-942f-rcfh |
| — | Microsoft.WindowsDesktop.App.Runtime.win-arm64 (NuGet) | 8.0.0 to before 8.0.32 | 8.0.32 | Patch available | GHSA-c27m-942f-rcfh |
| — | Microsoft.WindowsDesktop.App.Runtime.win-x64 (NuGet) | 8.0.0 to before 8.0.32 | 8.0.32 | Patch available | GHSA-c27m-942f-rcfh |
| — | Microsoft.WindowsDesktop.App.Runtime.win-x86 (NuGet) | 8.0.0 to before 8.0.32 | 8.0.32 | Patch available | GHSA-c27m-942f-rcfh |
| — | Microsoft.WindowsDesktop.App.Runtime.win-arm64 (NuGet) | 11.0.0-preview.1 to before 11.0.0-rc.2 | 11.0.0-rc.2 | Patch available | GHSA-c27m-942f-rcfh |
| — | Microsoft.WindowsDesktop.App.Runtime.win-x64 (NuGet) | 11.0.0-preview.1 to before 11.0.0-rc.2 | 11.0.0-rc.2 | Patch available | GHSA-c27m-942f-rcfh |
| — | Microsoft.WindowsDesktop.App.Runtime.win-x86 (NuGet) | 11.0.0-preview.1 to before 11.0.0-rc.2 | 11.0.0-rc.2 | Patch available | GHSA-c27m-942f-rcfh |
| — | Microsoft.WindowsDesktop.App.Runtime.win-arm64 (NuGet) | 10.0.0 to before 10.0.13 | 10.0.13 | Patch available | GHSA-c27m-942f-rcfh |
| — | Microsoft.WindowsDesktop.App.Runtime.win-x64 (NuGet) | 10.0.0 to before 10.0.13 | 10.0.13 | Patch available | GHSA-c27m-942f-rcfh |
| — | Microsoft.WindowsDesktop.App.Runtime.win-x86 (NuGet) | 10.0.0 to before 10.0.13 | 10.0.13 | Patch available | GHSA-c27m-942f-rcfh |
- .NET 10.0 runtime VendorMicrosoft Affected 10.0.0 to before 10.0.13 Fixed in 10.0.13 Patch available CNA
- .NET 11.0 runtime VendorMicrosoft Affected 11.0.0 to before 11.0.0-rc.2 Fixed in 11.0.0-rc.2 Patch available CNA
- .NET 8.0 runtime VendorMicrosoft Affected 8.0.0 to before 8.0.32 Fixed in 8.0.32 Patch available CNA
- .NET 9.0 runtime VendorMicrosoft Affected 9.0.0 to before 9.0.21 Fixed in 9.0.21 Patch available CNA
- Microsoft Visual Studio 2022 version 17.14 VendorMicrosoft Affected 17.14.0 to before 17.14.42 Fixed in 17.14.42 Patch available CNA
- Microsoft Visual Studio 2026 version 18.10 VendorMicrosoft Affected 18.10.0 to before 18.10.4 Fixed in 18.10.4 Patch available CNA
- Microsoft.WindowsDesktop.App.Runtime.win-arm64 (NuGet) Vendor— Affected 9.0.0 to before 9.0.21 Fixed in 9.0.21 Patch available GHSA-c27m-942f-rcfh
- Microsoft.WindowsDesktop.App.Runtime.win-x64 (NuGet) Vendor— Affected 9.0.0 to before 9.0.21 Fixed in 9.0.21 Patch available GHSA-c27m-942f-rcfh
- Microsoft.WindowsDesktop.App.Runtime.win-x86 (NuGet) Vendor— Affected 9.0.0 to before 9.0.21 Fixed in 9.0.21 Patch available GHSA-c27m-942f-rcfh
- Microsoft.WindowsDesktop.App.Runtime.win-arm64 (NuGet) Vendor— Affected 8.0.0 to before 8.0.32 Fixed in 8.0.32 Patch available GHSA-c27m-942f-rcfh
- Microsoft.WindowsDesktop.App.Runtime.win-x64 (NuGet) Vendor— Affected 8.0.0 to before 8.0.32 Fixed in 8.0.32 Patch available GHSA-c27m-942f-rcfh
- Microsoft.WindowsDesktop.App.Runtime.win-x86 (NuGet) Vendor— Affected 8.0.0 to before 8.0.32 Fixed in 8.0.32 Patch available GHSA-c27m-942f-rcfh
- Microsoft.WindowsDesktop.App.Runtime.win-arm64 (NuGet) Vendor— Affected 11.0.0-preview.1 to before 11.0.0-rc.2 Fixed in 11.0.0-rc.2 Patch available GHSA-c27m-942f-rcfh
- Microsoft.WindowsDesktop.App.Runtime.win-x64 (NuGet) Vendor— Affected 11.0.0-preview.1 to before 11.0.0-rc.2 Fixed in 11.0.0-rc.2 Patch available GHSA-c27m-942f-rcfh
- Microsoft.WindowsDesktop.App.Runtime.win-x86 (NuGet) Vendor— Affected 11.0.0-preview.1 to before 11.0.0-rc.2 Fixed in 11.0.0-rc.2 Patch available GHSA-c27m-942f-rcfh
- Microsoft.WindowsDesktop.App.Runtime.win-arm64 (NuGet) Vendor— Affected 10.0.0 to before 10.0.13 Fixed in 10.0.13 Patch available GHSA-c27m-942f-rcfh
- Microsoft.WindowsDesktop.App.Runtime.win-x64 (NuGet) Vendor— Affected 10.0.0 to before 10.0.13 Fixed in 10.0.13 Patch available GHSA-c27m-942f-rcfh
- Microsoft.WindowsDesktop.App.Runtime.win-x86 (NuGet) Vendor— Affected 10.0.0 to before 10.0.13 Fixed in 10.0.13 Patch available GHSA-c27m-942f-rcfh
Remediation
Update the .NET 8.0 runtime to 8.0.32, the .NET 9.0 runtime to 9.0.21, the .NET 10.0 runtime to 10.0.13, the .NET 11.0 runtime to 11.0.0-rc.2, Visual Studio 2022 version 17.14 to 17.14.42 and Visual Studio 2026 version 18.10 to 18.10.4. The Windows desktop runtime NuGet packages are fixed in 8.0.32, 9.0.21 and 11.0.0-rc.2. Red Hat fixes Red Hat Hardened Images in RHSA-2026:84693.
Written with Claude Haiku 5.5 from the sources below · 2026-10-28
- Fix · CNA .NET 10.0 runtime (Microsoft) Fixed in 10.0.13
- Fix · CNA .NET 11.0 runtime (Microsoft) Fixed in 11.0.0-rc.2
- Fix · CNA .NET 8.0 runtime (Microsoft) Fixed in 8.0.32
- Fix · CNA .NET 9.0 runtime (Microsoft) Fixed in 9.0.21
- Fix · CNA Microsoft Visual Studio 2022 version 17.14 (Microsoft) Fixed in 17.14.42
- Fix · CNA Microsoft Visual Studio 2026 version 18.10 (Microsoft) Fixed in 18.10.4
- Fix · GHSA-c27m-942f-rcfh Microsoft.WindowsDesktop.App.Runtime.win-arm64 (NuGet) Fixed in 9.0.21 Advisory →
- Fix · GHSA-c27m-942f-rcfh Microsoft.WindowsDesktop.App.Runtime.win-x64 (NuGet) Fixed in 9.0.21 Advisory →
- Fix · GHSA-c27m-942f-rcfh Microsoft.WindowsDesktop.App.Runtime.win-x86 (NuGet) Fixed in 9.0.21 Advisory →
- Fix · GHSA-c27m-942f-rcfh Microsoft.WindowsDesktop.App.Runtime.win-arm64 (NuGet) Fixed in 8.0.32 Advisory →
- Fix · GHSA-c27m-942f-rcfh Microsoft.WindowsDesktop.App.Runtime.win-x64 (NuGet) Fixed in 8.0.32 Advisory →
- Fix · GHSA-c27m-942f-rcfh Microsoft.WindowsDesktop.App.Runtime.win-x86 (NuGet) Fixed in 8.0.32 Advisory →
- Fix · GHSA-c27m-942f-rcfh Microsoft.WindowsDesktop.App.Runtime.win-arm64 (NuGet) Fixed in 11.0.0-rc.2 Advisory →
- Fix · GHSA-c27m-942f-rcfh Microsoft.WindowsDesktop.App.Runtime.win-x64 (NuGet) Fixed in 11.0.0-rc.2 Advisory →
- Fix · GHSA-c27m-942f-rcfh Microsoft.WindowsDesktop.App.Runtime.win-x86 (NuGet) Fixed in 11.0.0-rc.2 Advisory →
- Fix · GHSA-c27m-942f-rcfh Microsoft.WindowsDesktop.App.Runtime.win-arm64 (NuGet) Fixed in 10.0.13 Advisory →
- Fix · GHSA-c27m-942f-rcfh Microsoft.WindowsDesktop.App.Runtime.win-x64 (NuGet) Fixed in 10.0.13 Advisory →
- Fix · GHSA-c27m-942f-rcfh Microsoft.WindowsDesktop.App.Runtime.win-x86 (NuGet) Fixed in 10.0.13 Advisory →
Red Hat 1 advisory
- RHSA-2026:84693 Released 2026-10-19 · Red Hat rating ImportantRed Hat Hardened Images RPMs Security Update
- Red Hat Hardened Images aspnetcore-runtime-8.0-8.0.32-0.1.hum1@aarch64, aspnetcore-runtime-8.0-8.0.32-0.1.hum1@x86_64, aspnetcore-runtime-dbg-8.0-8.0.32-0.1.hum1@aarch64 +22
Vendor assessments
Red Hat
Red Hat rating: Important. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Hardened Images | Fixed | RHSA-2026:84693 |
Not affected: 1 product
- Red Hat Hardened Images
Timeline
- 2026-10-13 Threatist record created from CVE-2026-87697
- 2026-10-13 Alias added: GHSA-c27m-942f-rcfh
- 2026-10-13 Fix available: NuGet/[email protected], NuGet/[email protected], NuGet/[email protected] +9 · GHSA-c27m-942f-rcfh
- 2026-10-13 CVSS score added · GHSA-c27m-942f-rcfh
- 2026-10-13 Weakness changed · GHSA-c27m-942f-rcfh
- 2026-10-13 4 new references · GHSA-c27m-942f-rcfh
- 2026-10-14 CISA SSVC decision points changed
- 2026-10-14 Priority changed: LOW → MEDIUM
- 2026-10-18 Affected versions changed · Red Hat
- 2026-10-20 2 new references · GHSA-c27m-942f-rcfh
- 2026-10-20 Fix available: RHSA-2026:84693 · Red Hat
- 2026-10-20 Fix available: Red Hat Hardened Images · Red Hat
- 2026-10-23 Fix available: Microsoft/.NET 10.0 [email protected], Microsoft/.NET 11.0 [email protected], Microsoft/.NET 8.0 [email protected] +1 · CNA
References
More Microsoft vulnerabilities
- TI-2026-42212 Microsoft SharePoint Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
- TI-2026-37256 Microsoft SharePoint Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
- TI-2026-26194 Windows Internet Key Exchange (IKE) Service Extensions Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
- TI-2026-16982 Microsoft SharePoint Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
- TI-2025-36863 Windows Server Update Service (WSUS) Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
- TI-2025-33671 Microsoft SharePoint Server Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
Sources
- CVE-2026-87697 · CVE Program
- CVE-2026-87697 · NVD
- FIRST EPSS
- GHSA-c27m-942f-rcfh · GitHub Advisory Database · CC BY 4.0
- CVE-2026-87697 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences