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Microsoft Security Response CenterCVE-2026-62899

.NET Security Feature Bypass Vulnerability

HighVendor CVSS 5.9 / 10 1 CVE Published Aug 11, 2026 at 7:00 AM UTC
Get alerts for NET 10.0 installed on Mac OS

Summary

Inconsistent interpretation of http requests ('http request/response smuggling') in .NET allows an unauthorized attacker to bypass a security feature over a network.

Products covered

  • .NET 10.0 installed on Mac OS

  • .NET 10.0 installed on Linux

  • .NET 8.0 installed on Windows

  • .NET 8.0 installed on Linux

  • .NET 8.0 installed on Mac OS

  • .NET 9.0 installed on Linux

  • .NET 9.0 installed on Mac OS

  • .NET 9.0 installed on Windows

Show 2 more products

  • Microsoft Visual Studio 2022 version 17.14

  • Microsoft Visual Studio 2026 version 18.8

Remediation

Install KB5122106. Install KB5122104. Install KB5122105.

Vendor-listed fixes

  • 10.0.11

  • 8.0.30

  • 9.0.19

  • 17.14.38

  • 18.8.3

CVEs in this advisory 1

CVE-2026-62899
Update history

What changed in later vendor updates

SecurityAlert records field-level changes from the point we begin following a bulletin. Earlier vendor changes may not have a field-by-field record.

    • The vendor changed its remediation guidance.

Updates

  1. Published by Microsoft Security Response Center

    The publication date reported by the vendor.

  2. Added to SecurityAlert

    We collected the advisory from the official source.

  3. Confirmed at the source

    Our collector saw this advisory during a later source check.

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