CVE-2026-25667 Denial of service in n/a

What is CVE-2026-25667?

CVE-2026-25667 is a high-severity denial of service vulnerability in Microsoft .Net, published on 19 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

ASP.NET Core Kestrel in Microsoft .NET 8.0 before 8.0.22 and .NET 9.0 before 9.0.11 allows a remote attacker to cause excessive CPU consumption by sending a crafted QUIC packet, because of an incorrect exit condition for HTTP/3 Encoder/Decoder stream processing.

Weakness: CWE-400

Which versions are affected by CVE-2026-25667?

2 open source packages ship an affected version, including dotnet and dotnet-sdk. It affects 1 product.

Products include Microsoft .Net.

How do I fix CVE-2026-25667?

Upgrade dotnet to a fixed version for your release line: 8.0.22 or 9.0.11.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2026-25667 being exploited?

There is no known exploitation of CVE-2026-25667 in the wild and no public exploit code.

Other vulnerabilities in Microsoft .Net

• CVE-2024-43498 .NET and Visual Studio Remote Code Execution Vulnerability Critical 9.8
• CVE-2024-0057 NET, .NET Framework, and Visual Studio Security Feature Bypass Vulnerability Critical 9.1
• CVE-2026-96957 .NET Security Feature Bypass Vulnerability High 8.8
• CVE-2026-69439 .NET and Visual Studio Elevation of Privilege Vulnerability High 8.8
• CVE-2026-71328 .NET and Visual Studio Remote Code Execution Vulnerability High 8.8

All Microsoft .Net vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BIT-dotnet-2026-25667, BIT-dotnet-sdk-2026-25667, GHSA-jc8w-j2q2-vwjx, MINI-4xj4-jqfh-j879, MINI-9mr2-2hf7-crmq.