Live › vulnerability › CVE-2026-66822
Go to dashboardSocketsHttpHandler in .NET can keep a Proxy-Authorization header when following an HTTP redirect, so basic proxy credentials are sent to the redirect destination server. An attacker who can make the request land on a server they control, for example through a redirect they can influence, gets the proxy username and password.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-10-23 19:11 UTC, 5h before NVD. All times on this page are UTC.
| Product | Ecosystem | Affected | Fixed in |
|---|---|---|---|
| Microsoft.NETCore.App.Runtime.linux-arm | nuget | >= 9.0.0, <= 9.0.20 | 9.0.21 |
| Microsoft.NETCore.App.Runtime.linux-arm64 | nuget | >= 9.0.0, <= 9.0.20 | 9.0.21 |
| Microsoft.NETCore.App.Runtime.linux-musl-arm | nuget | >= 9.0.0, <= 9.0.20 | 9.0.21 |
| Microsoft.NETCore.App.Runtime.linux-musl-arm64 | nuget | >= 9.0.0, <= 9.0.20 | 9.0.21 |
| Microsoft.NETCore.App.Runtime.linux-musl-x64 | nuget | >= 9.0.0, <= 9.0.20 | 9.0.21 |
| Microsoft.NETCore.App.Runtime.linux-x64 | nuget | >= 9.0.0, <= 9.0.20 | 9.0.21 |
| Microsoft.NETCore.App.Runtime.osx-arm64 | nuget | >= 9.0.0, <= 9.0.20 | 9.0.21 |
| Microsoft.NETCore.App.Runtime.osx-x64 | nuget | >= 9.0.0, <= 9.0.20 | 9.0.21 |
| Microsoft.NETCore.App.Runtime.win-arm64 |
| nuget |
| >= 9.0.0, <= 9.0.20 |
| 9.0.21 |
| Microsoft.NETCore.App.Runtime.win-x64 | nuget | >= 9.0.0, <= 9.0.20 | 9.0.21 |
| Microsoft.NETCore.App.Runtime.win-x86 | nuget | >= 9.0.0, <= 9.0.20 | 9.0.21 |
| Microsoft.NETCore.App.Runtime.linux-arm | nuget | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 |
| Microsoft.NETCore.App.Runtime.linux-arm64 | nuget | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 |
| Microsoft.NETCore.App.Runtime.linux-musl-arm | nuget | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 |
| Microsoft.NETCore.App.Runtime.linux-musl-arm64 | nuget | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 |
| Microsoft.NETCore.App.Runtime.linux-musl-x64 | nuget | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 |
| Microsoft.NETCore.App.Runtime.linux-x64 | nuget | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 |
| Microsoft.NETCore.App.Runtime.osx-arm64 | nuget | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 |
| Microsoft.NETCore.App.Runtime.osx-x64 | nuget | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 |
| Microsoft.NETCore.App.Runtime.win-arm64 | nuget | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 |
| Microsoft.NETCore.App.Runtime.win-x64 | nuget | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 |
| Microsoft.NETCore.App.Runtime.win-x86 | nuget | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 |
| Microsoft.NETCore.App.Runtime.linux-arm | nuget | >= 10.0.0, <= 10.0.12 | 10.0.13 |
| Microsoft.NETCore.App.Runtime.linux-arm64 | nuget | >= 10.0.0, <= 10.0.12 | 10.0.13 |
| Microsoft.NETCore.App.Runtime.linux-musl-arm | nuget | >= 10.0.0, <= 10.0.12 | 10.0.13 |
| Microsoft.NETCore.App.Runtime.linux-musl-arm64 | nuget | >= 10.0.0, <= 10.0.12 | 10.0.13 |
| Microsoft.NETCore.App.Runtime.linux-musl-x64 | nuget | >= 10.0.0, <= 10.0.12 | 10.0.13 |
| Microsoft.NETCore.App.Runtime.linux-x64 | nuget | >= 10.0.0, <= 10.0.12 | 10.0.13 |
| Microsoft.NETCore.App.Runtime.osx-arm64 | nuget | >= 10.0.0, <= 10.0.12 | 10.0.13 |
| Microsoft.NETCore.App.Runtime.osx-x64 | nuget | >= 10.0.0, <= 10.0.12 | 10.0.13 |
| Microsoft.NETCore.App.Runtime.win-arm64 | nuget | >= 10.0.0, <= 10.0.12 | 10.0.13 |
| Microsoft.NETCore.App.Runtime.win-x64 | nuget | >= 10.0.0, <= 10.0.12 | 10.0.13 |
| Microsoft.NETCore.App.Runtime.win-x86 | nuget | >= 10.0.0, <= 10.0.12 | 10.0.13 |
| Microsoft.NETCore.App.Runtime.linux-arm | nuget | >= 8.0.0, <= 8.0.31 | 8.0.32 |
| Microsoft.NETCore.App.Runtime.linux-arm64 | nuget | >= 8.0.0, <= 8.0.31 | 8.0.32 |
| Microsoft.NETCore.App.Runtime.linux-musl-arm | nuget | >= 8.0.0, <= 8.0.31 | 8.0.32 |
| Microsoft.NETCore.App.Runtime.linux-musl-arm64 | nuget | >= 8.0.0, <= 8.0.31 | 8.0.32 |
| Microsoft.NETCore.App.Runtime.linux-musl-x64 | nuget | >= 8.0.0, <= 8.0.31 | 8.0.32 |
| Microsoft.NETCore.App.Runtime.linux-x64 | nuget | >= 8.0.0, <= 8.0.31 | 8.0.32 |
| Microsoft.NETCore.App.Runtime.osx-arm64 | nuget | >= 8.0.0, <= 8.0.31 | 8.0.32 |
| Microsoft.NETCore.App.Runtime.osx-x64 | nuget | >= 8.0.0, <= 8.0.31 | 8.0.32 |
| Microsoft.NETCore.App.Runtime.win-arm64 | nuget | >= 8.0.0, <= 8.0.31 | 8.0.32 |
| Microsoft.NETCore.App.Runtime.win-x64 | nuget | >= 8.0.0, <= 8.0.31 | 8.0.32 |
| Microsoft.NETCore.App.Runtime.win-x86 | nuget | >= 8.0.0, <= 8.0.31 | 8.0.32 |
dotnet --info and check the installed Microsoft.NETCore.App runtime version; affected 9.0.x is 9.0.20 or lower, 10.0.x is 10.0.12 or lower, 8.0.x is 8.0.31 or lower, and 11.0 preview/rc through rc.1dotnet list package and look for Microsoft.NETCore.App.Runtime.* at affected versions9.0.21 or later for 9.0, 10.0.13 or later for 10.0, 8.0.32 or later for 8.0, 11.0.0-rc.2 or later for 11 previews; restart apps and recompile and redeploy self-contained appsEach row is the first time that source carried this signal. The analyst’s rows are its own findings.
Microsoft is releasing this security advisory to provide information about a vulnerability in System.Net.Http. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability.
SocketsHttpHandler can retain a Proxy-Authorization header across an HTTP redirect and leak basic proxy credentials to the destination server.
Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/448
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:NThe vulnerability affects Microsoft .NET projects that use an affected package version listed below.
| Package name | Affected version | Patched version |
|---|---|---|
| Microsoft.NETCore.App.Runtime.linux-arm | >= 9.0.0, <= 9.0.20 | 9.0.21 |
| Microsoft.NETCore.App.Runtime.linux-arm64 | >= 9.0.0, <= 9.0.20 | 9.0.21 |
| Microsoft.NETCore.App.Runtime.linux-musl-arm | >= 9.0.0, <= 9.0.20 | 9.0.21 |
| Microsoft.NETCore.App.Runtime.linux-musl-arm64 | >= 9.0.0, <= 9.0.20 | 9.0.21 |
| Microsoft.NETCore.App.Runtime.linux-musl-x64 | >= 9.0.0, <= 9.0.20 | 9.0.21 |
| Microsoft.NETCore.App.Runtime.linux-x64 | >= 9.0.0, <= 9.0.20 | 9.0.21 |
| Microsoft.NETCore.App.Runtime.osx-arm64 | >= 9.0.0, <= 9.0.20 | 9.0.21 |
This page as .md · .json · in your agent: get_signal("CVE-2026-66822")
GitHub Advisory Database, CC-BY 4.0 · NVD data is provided by NIST and is public domain. Posts quoted belong to their authors.
| Microsoft.NETCore.App.Runtime.osx-x64 |
| >= 9.0.0, <= 9.0.20 |
| 9.0.21 |
| Microsoft.NETCore.App.Runtime.win-arm | >= 9.0.0, <= 9.0.20 | 9.0.21 |
| Microsoft.NETCore.App.Runtime.win-arm64 | >= 9.0.0, <= 9.0.20 | 9.0.21 |
| Microsoft.NETCore.App.Runtime.win-x64 | >= 9.0.0, <= 9.0.20 | 9.0.21 |
| Microsoft.NETCore.App.Runtime.win-x86 | >= 9.0.0, <= 9.0.20 | 9.0.21 |
| Microsoft.NETCore.App.Runtime.linux-arm | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 |
| Microsoft.NETCore.App.Runtime.linux-arm64 | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 |
| Microsoft.NETCore.App.Runtime.linux-musl-arm | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 |
| Microsoft.NETCore.App.Runtime.linux-musl-arm64 | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 |
| Microsoft.NETCore.App.Runtime.linux-musl-x64 | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 |
| Microsoft.NETCore.App.Runtime.linux-x64 | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 |
| Microsoft.NETCore.App.Runtime.osx-arm64 | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 |
| Microsoft.NETCore.App.Runtime.osx-x64 | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 |
| Microsoft.NETCore.App.Runtime.win-arm | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 |
| Microsoft.NETCore.App.Runtime.win-arm64 | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 |
| Microsoft.NETCore.App.Runtime.win-x64 | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 |
| Microsoft.NETCore.App.Runtime.win-x86 | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 |
| Microsoft.NETCore.App.Runtime.linux-arm | >= 10.0.0, <= 10.0.12 | 10.0.13 |
| Microsoft.NETCore.App.Runtime.linux-arm64 | >= 10.0.0, <= 10.0.12 | 10.0.13 |
| Microsoft.NETCore.App.Runtime.linux-musl-arm | >= 10.0.0, <= 10.0.12 | 10.0.13 |
| Microsoft.NETCore.App.Runtime.linux-musl-arm64 | >= 10.0.0, <= 10.0.12 | 10.0.13 |
| Microsoft.NETCore.App.Runtime.linux-musl-x64 | >= 10.0.0, <= 10.0.12 | 10.0.13 |
| Microsoft.NETCore.App.Runtime.linux-x64 | >= 10.0.0, <= 10.0.12 | 10.0.13 |
| Microsoft.NETCore.App.Runtime.osx-arm64 | >= 10.0.0, <= 10.0.12 | 10.0.13 |
| Microsoft.NETCore.App.Runtime.osx-x64 | >= 10.0.0, <= 10.0.12 | 10.0.13 |
| Microsoft.NETCore.App.Runtime.win-arm | >= 10.0.0, <= 10.0.12 | 10.0.13 |
| Microsoft.NETCore.App.Runtime.win-arm64 | >= 10.0.0, <= 10.0.12 | 10.0.13 |
| Microsoft.NETCore.App.Runtime.win-x64 | >= 10.0.0, <= 10.0.12 | 10.0.13 |
| Microsoft.NETCore.App.Runtime.win-x86 | >= 10.0.0, <= 10.0.12 | 10.0.13 |
| Microsoft.NETCore.App.Runtime.linux-arm | >= 8.0.0, <= 8.0.31 | 8.0.32 |
| Microsoft.NETCore.App.Runtime.linux-arm64 | >= 8.0.0, <= 8.0.31 | 8.0.32 |
| Microsoft.NETCore.App.Runtime.linux-musl-arm | >= 8.0.0, <= 8.0.31 | 8.0.32 |
| Microsoft.NETCore.App.Runtime.linux-musl-arm64 | >= 8.0.0, <= 8.0.31 | 8.0.32 |
| Microsoft.NETCore.App.Runtime.linux-musl-x64 | >= 8.0.0, <= 8.0.31 | 8.0.32 |
| Microsoft.NETCore.App.Runtime.linux-x64 | >= 8.0.0, <= 8.0.31 | 8.0.32 |
| Microsoft.NETCore.App.Runtime.osx-arm64 | >= 8.0.0, <= 8.0.31 | 8.0.32 |
| Microsoft.NETCore.App.Runtime.osx-x64 | >= 8.0.0, <= 8.0.31 | 8.0.32 |
| Microsoft.NETCore.App.Runtime.win-arm | >= 8.0.0, <= 8.0.31 | 8.0.32 |
| [Microsoft.NETCo |