CVE-2026-62899

## Executive summary Microsoft is releasing this security advisory to provide information about a vulnerability in System.Net.HttpListener. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability. Inconsistent interpretation of http requests ('http request/response smuggling') in .NET allows an unauthorized attacker to bypass a security feature over a network. ## Announcement Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/427 ## CVSS Details - **Version:** 3.1 - **Severity:** Medium - **Score:** 5.9 - **Vector:** `CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C` - **Weakness:** CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') ## Affected Platforms - **Platforms:** Linux, macOS - **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.NETCore.App.Runtime.linux-arm](https://www.nuget.org/packages/Microsoft.NETCore.App.Runtime.linux-arm) | >= 10.0.0, <= 10.0.10 | 10.0.11 [Microsoft.NETCore.App.Runtime.linux-arm64](https://www.nuget.org/packages/Microsoft.NETCore.App.Runtime.linux-arm64) | >= 10.0.0, <= 10.0.10 | 10.0.11 [Microsoft.NETCore.App.Runtime.linux-musl-arm](https://www.nuget.org/packages/Microsoft.NETCore.App.Runtime.linux-musl-arm) | >= 10.0.0, <= 10.0.10 | 10.0.11 [Microsoft.NETCore.App.Runtime.linux-musl-arm64](https://www.nuget.org/packages/Microsoft.NETCore.App.Runtime.linux-musl-arm64) | >= 10.0.0, <= 10.0.10 | 10.0.11 [Microsoft.NETCore.App.Runtime.linux-musl-x64](https://www.nuget.org/packages/Microsoft.NETCore.App.Runtime.linux-musl-x64) | >= 10.0.0, <= 10.0.10 | 10.0.11 [Microsoft.NETCore.App.Runtime.li