Inconsistent interpretation of HTTP requests in Microsoft products - CVE-2026-62899

Vulnerability identifier: #VU141790

CSH Severity: Medium

CVSS v4: 8.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-62899

CWE-ID: CWE-444

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to bypass a security feature.

The vulnerability exists due to inconsistent interpretation of http requests in .NET when handling http requests. A remote attacker can send crafted http requests to bypass a security feature.

Successful exploitation requires the target system to be configured in a specific manner and knowledge of that setup.

.NET
Visual Studio
.NET for Linux
.NET for macOS
Red Hat Enterprise Linux for IBM z Systems
Red Hat CodeReady Linux Builder for IBM z Systems
Red Hat CodeReady Linux Builder for ARM 64
Red Hat CodeReady Linux Builder for Power, little endian
Red Hat CodeReady Linux Builder for x86_64
Red Hat Enterprise Linux for ARM 64
Red Hat Enterprise Linux for Power, little endian
Red Hat Enterprise Linux for x86_64
Red Hat Enterprise Linux for ARM 64 - Extended Update Support
Red Hat Enterprise Linux for x86_64 - Extended Update Support
Red Hat Enterprise Linux for IBM z Systems - Extended Update Support
Red Hat Enterprise Linux for Power, little endian - Extended Update Support
Red Hat CodeReady Linux Builder for x86_64 - Extended Update Support
Red Hat CodeReady Linux Builder for Power, little endian - Extended Update Support
Red Hat CodeReady Linux Builder for IBM z Systems - Extended Update Support
Red Hat CodeReady Linux Builder for ARM 64 - Extended Update Support
Ubuntu
Fedora
dotnet10 (Ubuntu package)
dotnet8.0 (Red Hat package)
dotnet8.0
dotnet9.0 (Red Hat package)
dotnet9.0
dotnet10.0 (Red Hat package)
dotnet10.0

Install security update from vendor's website.

.NET - addressed in versions 8.0.30, 9.0.19
Visual Studio - update to 17.14.38
.NET for Linux - addressed in versions 8.0.30, 9.0.19
.NET for macOS - addressed in versions 8.0.30, 9.0.19
dotnet10 (Ubuntu package) - addressed in versions 8.0.30-0ubuntu1~22.04.1, 8.0.30-0ubuntu1~24.04.1, 8.0.130-0ubuntu1~22.04.1, 8.0.130-0ubuntu1~24.04.1, 8.0.130-8.0.30-0ubuntu1~22.04.1, 8.0.130-8.0.30-0ubuntu1~24.04.1, 10.0.11-0ubuntu1~24.04.1, 10.0.11-0ubuntu1~26.04.1, 10.0.111-0ubuntu1~24.04.1, 10.0.111-0ubuntu1~26.04.1, 10.0.111-10.0.11-0ubuntu1~24.04.1, 10.0.111-10.0.11-0ubuntu1~26.04.1
dotnet8.0 (Red Hat package) - addressed in versions 8.0.130-1.el8_10, 8.0.130-1.el10_0, 8.0.130-1.el10_2
dotnet8.0 - addressed in versions 8.0.130-1.fc43, 8.0.130-1.fc44
dotnet9.0 (Red Hat package) - update to 9.0.120-1.el10_0
dotnet9.0 - addressed in versions 9.0.120-1.fc43, 9.0.120-1.fc44
dotnet10.0 (Red Hat package) - addressed in versions 10.0.111-1.el8_10, 10.0.111-1.el10_2
dotnet10.0 - addressed in versions 10.0.111-1.fc43, 10.0.111-1.fc44

• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2026-62899
• https://support.microsoft.com/help/5122106

• Multiple vulnerabilities in Microsoft .NET Framework
• Red Hat Enterprise Linux 8 update for .NET 8.0
• Red Hat Enterprise Linux 10 update for .NET 8.0
• Red Hat Enterprise Linux 8 update for .NET 10.0
• Fedora 43 update for dotnet10.0
• Fedora 44 update for dotnet10.0
• Fedora 43 update for dotnet8.0
• Fedora 44 update for dotnet8.0
• Fedora 43 update for dotnet9.0
• Fedora 44 update for dotnet9.0
• Red Hat Enterprise Linux 10 update for .NET 10.0
• Ubuntu update for dotnet10
• Red Hat Enterprise Linux 10 update for .NET 8.0
• Red Hat Enterprise Linux 10 update for .NET 9.0