Microsoft Security Advisory CVE-2026-70188 - ASP.NET Core Security Feature Bypass Vulnerability

Code

The project this record applies to. Exploit listings stay in References.

• microsoft.aspnetcore.app.runtime.linux-arm64 · nuget.org
• microsoft.aspnetcore.app.runtime.linux-musl-arm64 · nuget.org
• microsoft.aspnetcore.app.runtime.osx-arm64 · nuget.org
• microsoft.aspnetcore.app.runtime.win-x86 · nuget.org

Timeline

Detection, updates, and resolution for this record.

1. Oct 13, 2026 · GitLab Advisory Database

   Detected

   Microsoft is releasing this security advisory to provide information about a vulnerability in Microsoft.AspNetCore.Server.Kestrel.Core. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability. Kestrel accepts newline characters in HTTP/2 request trailers and values retrieved from the dynamic HPACK table instead of treating them as ma

Affected

• nuget microsoft.aspnetcore.app.runtime.linux-arm64version unspecified
• nuget microsoft.aspnetcore.app.runtime.linux-musl-arm64version unspecified
• nuget microsoft.aspnetcore.app.runtime.osx-arm64version unspecified
• nuget microsoft.aspnetcore.app.runtime.win-x86version unspecified

Sources

• CVE.orgVulnerability recordCVE-2026-70188

  Official CVE identifier

  cve.org
• FIRST EPSSExploitation probabilityCVE-2026-70188

  30-day exploitation probability 0.8%

  first.org
• GitLab Advisory DatabasePackage advisoryCVE-2026-70188

  Microsoft is releasing this security advisory to provide information about a vulnerability in Microsoft.AspNetCore.Server.Kestrel.Core. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability. Kestrel accepts newline characters in HTTP/2 request trailers and values retrieved from the dynamic HPACK table instead of treating them as ma

  advisories.gitlab.com