Improper Encoding or Escaping of Output in Visual Studio - CVE-2026-109476

Vulnerability identifier: #VU164740

CSH Severity: Medium

CVSS v4: 5.9 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-109476

CWE-ID: CWE-116

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to disclose sensitive information, including cookie data and cached sessions.

The vulnerability exists due to improper encoding or escaping of output in ASP.NET Core when generating output. A remote attacker can exploit the improperly encoded or escaped output, with user interaction, to bypass protections against reading cookies and disclose sensitive session information.

Visual Studio
Ubuntu
aspnetcore-runtime-8.0 (Ubuntu package)
dotnet-hostfxr-8.0 (Ubuntu package)
dotnet-runtime-8.0 (Ubuntu package)
dotnet-host-8.0 (Ubuntu package)
dotnet-sdk-8.0 (Ubuntu package)
dotnet8 (Ubuntu package)
aspnetcore-runtime-10.0 (Ubuntu package)
dotnet-host-10.0 (Ubuntu package)
dotnet-hostfxr-10.0 (Ubuntu package)
dotnet-runtime-10.0 (Ubuntu package)
dotnet-sdk-10.0 (Ubuntu package)
dotnet-sdk-aot-10.0 (Ubuntu package)
dotnet10 (Ubuntu package)
aspnetcore-runtime-11.0 (Ubuntu package)
dotnet-host-11.0 (Ubuntu package)
dotnet-hostfxr-11.0 (Ubuntu package)
dotnet-runtime-11.0 (Ubuntu package)
dotnet-sdk-11.0 (Ubuntu package)
dotnet-sdk-aot-11.0 (Ubuntu package)
dotnet11 (Ubuntu package)

Install security update from vendor's website.

Visual Studio - update to 17.14.45
aspnetcore-runtime-8.0 (Ubuntu package) - addressed in versions 8.0.34-0ubuntu1~22.04.1, 8.0.34-0ubuntu1~24.04.1
dotnet-hostfxr-8.0 (Ubuntu package) - addressed in versions 8.0.34-0ubuntu1~22.04.1, 8.0.34-0ubuntu1~24.04.1
dotnet-runtime-8.0 (Ubuntu package) - addressed in versions 8.0.34-0ubuntu1~22.04.1, 8.0.34-0ubuntu1~24.04.1
dotnet-host-8.0 (Ubuntu package) - addressed in versions 8.0.34-0ubuntu1~22.04.1, 8.0.34-0ubuntu1~24.04.1
dotnet-sdk-8.0 (Ubuntu package) - addressed in versions 8.0.134-0ubuntu1~22.04.1, 8.0.134-0ubuntu1~24.04.1
dotnet8 (Ubuntu package) - addressed in versions 8.0.134-8.0.34-0ubuntu1~22.04.1, 8.0.134-8.0.34-0ubuntu1~24.04.1
aspnetcore-runtime-10.0 (Ubuntu package) - addressed in versions 10.0.15-0ubuntu1~24.04.1, 10.0.15-0ubuntu1~26.04.1, 10.0.15-0ubuntu1~26.10.1
dotnet-host-10.0 (Ubuntu package) - addressed in versions 10.0.15-0ubuntu1~24.04.1, 10.0.15-0ubuntu1~26.04.1, 10.0.15-0ubuntu1~26.10.1
dotnet-hostfxr-10.0 (Ubuntu package) - addressed in versions 10.0.15-0ubuntu1~24.04.1, 10.0.15-0ubuntu1~26.04.1, 10.0.15-0ubuntu1~26.10.1
dotnet-runtime-10.0 (Ubuntu package) - addressed in versions 10.0.15-0ubuntu1~24.04.1, 10.0.15-0ubuntu1~26.04.1, 10.0.15-0ubuntu1~26.10.1
dotnet-sdk-10.0 (Ubuntu package) - addressed in versions 10.0.115-0ubuntu1~24.04.1, 10.0.115-0ubuntu1~26.04.1, 10.0.115-0ubuntu1~26.10.1
dotnet-sdk-aot-10.0 (Ubuntu package) - addressed in versions 10.0.115-0ubuntu1~24.04.1, 10.0.115-0ubuntu1~26.04.1, 10.0.115-0ubuntu1~26.10.1
dotnet10 (Ubuntu package) - addressed in versions 10.0.115-10.0.15-0ubuntu1~24.04.1, 10.0.115-10.0.15-0ubuntu1~26.04.1, 10.0.115-10.0.15-0ubuntu1~26.10.1
aspnetcore-runtime-11.0 (Ubuntu package) - update to 11.0.0-0ubuntu1~26.10.1
dotnet-host-11.0 (Ubuntu package) - update to 11.0.0-0ubuntu1~26.10.1
dotnet-hostfxr-11.0 (Ubuntu package) - update to 11.0.0-0ubuntu1~26.10.1
dotnet-runtime-11.0 (Ubuntu package) - update to 11.0.0-0ubuntu1~26.10.1
dotnet-sdk-11.0 (Ubuntu package) - update to 11.0.100-0ubuntu1~26.10.1
dotnet-sdk-aot-11.0 (Ubuntu package) - update to 11.0.100-0ubuntu1~26.10.1
dotnet11 (Ubuntu package) - update to 11.0.100-11.0.0-0ubuntu1~26.10.1

• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2026-109476
• https://support.microsoft.com/help/5135243

• Multiple vulnerabilities in Visual Studio
• Ubuntu update for dotnet10, dotnet11, dotnet8