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Microsoft Security Response CenterCVE-2026-58649

.NET Information Disclosure Vulnerability

Origin validation error in .NET allows an unauthorized attacker to disclose information over a network.

Read the vendor bulletin Get alerts for Microsoft Visual Studio
6.5CVSS out of 10High severity
Scope

What the vendor says is affected

  • Microsoft Visual Studio 2022 version 17.14
  • .NET 11.0 installed on Linux
  • .NET 11.0 installed on Mac OS
  • .NET 8.0 installed on Windows
  • .NET 8.0 installed on Mac OS
  • .NET 8.0 installed on Linux
  • .NET 9.0 installed on Mac OS
  • .NET 9.0 installed on Windows
  • .NET 9.0 installed on Linux
  • Microsoft Visual Studio 2026 version 18.9
  • .NET 11.0 installed on Windows
  • .NET 10.0 installed on Windows
  • .NET 10.0 installed on Linux
  • .NET 10.0 installed on Mac OS

Versions the vendor lists as fixed

  • 17.14.40
  • 11.0 RC1
  • 8.0.130, 8.0.424
  • 9.0.120, 9.0.317
  • 18.9.3
  • 10.0.111, 10.0.400
Next step

What the vendor recommends

Release Notes Install KB5126104. Install KB5126105. Install KB5126106.

Review the complete instructions on the vendor's site
Timeline

When this advisory changed

  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.

Vulnerabilities

CVEs named in this advisory

CVE-2026-58649View CVSS, KEV, EPSS, and threat context
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