CVE-2026-109476

## Executive summary Microsoft is releasing this security advisory to provide information about a vulnerability in ASP.NET Core. This advisory provides guidance on updating affected applications and components. A crafted `X-Forwarded-Prefix` can inject cookie path delimiters unless PathBase-derived cookie paths percent-encode semicolons. ## Announcement Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/508 ## CVSS Details - **Version:** 3.1 - **Severity:** Medium - **Score:** 6.1 (base score) - **Vector:** `CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:N/A:N/E:U/RL:O/RC:C` - **Weakness:** CWE-116 ## Affected Platforms - **Platforms:** Windows, Linux, macOS - **Architectures:** All ## <a name="affected-packages"></a>Affected Packages The tables list affected version ranges and fixed package versions. Runtime and standalone deliveries are listed separately. ### .NET 8.0 - affected runtime packages Package | Affected version | Patched version --- | --- | --- [Microsoft.AspNetCore.App.Runtime.linux-arm](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.linux-arm) | >= 8.0.0-rc.1.23421.29, <= 8.0.33 | 8.0.34 [Microsoft.AspNetCore.App.Runtime.linux-arm64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.linux-arm64) | >= 8.0.0-rc.1.23421.29, <= 8.0.33 | 8.0.34 [Microsoft.AspNetCore.App.Runtime.linux-musl-arm](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.linux-musl-arm) | >= 8.0.0-rc.1.23421.29, <= 8.0.33 | 8.0.34 [Microsoft.AspNetCore.App.Runtime.linux-musl-arm64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.linux-musl-arm64) | >= 8.0.0-rc.1.23421.29, <= 8.0.33 | 8.0.34 [Microsoft.AspNetCore.App.Runtime.linux-musl-x64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.linux-musl-x64) | >= 8.0.0-rc.1.23421.29, <= 8.0.33 | 8.0.34 [Microsoft.AspNetCore.App.Runtime.linux-x64](https://www.nuget.org/packages/Microsoft.AspNetCore.App.Runtime.linux-x64) |