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Microsoft Security Response CenterCVE-2026-92707

MessagePack-CSharp Denial of Service Vulnerability

MediumVendor CVSS 5.3 / 10 1 CVE Published Oct 13, 2026 at 7:00 AM UTC
Get alerts for System.Formats.Cbor on .NET 10.0 installed on Windows

Summary

Improperly controlled sequential memory allocation in .NET allows an unauthorized attacker to deny service over a network.

Products covered

  • System.Formats.Cbor on .NET 10.0 installed on Windows

  • System.Formats.Cbor on .NET 10.0 installed on Linux

  • System.Formats.Cbor on .NET 10.0 installed on Mac OS

  • Microsoft.AspNetCore.SignalR.Protocols.MessagePack on .NET 11.0 installed on Windows

  • Microsoft.AspNetCore.SignalR.Protocols.MessagePack on .NET 11.0 installed on Linux

  • Microsoft.AspNetCore.SignalR.Protocols.MessagePack on .NET 11.0 installed on Mac OS

  • System.Formats.Cbor on .NET 8.0 installed on Windows

  • System.Formats.Cbor on .NET 8.0 installed on Linux

Show 7 more products

  • System.Formats.Cbor on .NET 8.0 installed on Mac OS

  • System.Formats.Cbor on .NET 9.0 installed on Windows

  • System.Formats.Cbor on .NET 9.0 installed on Linux

  • System.Formats.Cbor on .NET 9.0 installed on Mac OS

  • Microsoft Visual Studio 2026 version 18.10

  • Microsoft Visual Studio 2022 version 17.14

  • Microsoft Edge (Chromium-based)

Remediation

Release Notes

Vendor-listed fixes

  • 10.0.13

  • 11.0.0-rc.2

  • 8.0.32

  • 9.0.21

  • 18.10.4

  • 17.14.42

  • 2.5.303

  • 3.1.9

CVEs in this advisory 1

CVE-2026-92707
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.

    • Added affected products: Microsoft Edge (Chromium-based).
    • Removed affected products: MessagePack 2.5.303.
    • Added affected products: System.Formats.Cbor on .NET 8.0 installed on Linux, System.Formats.Cbor on .NET 8.0 installed on Mac OS, System.Formats.Cbor on .NET 8.0 installed on Windows, System.Formats.Cbor on .NET 9.0 installed on Linux....
    • Removed affected products: Microsoft.AspNetCore.SignalR.Protocols.MessagePack on .NET 8.0 installed on Linux, Microsoft.AspNetCore.SignalR.Protocols.MessagePack on .NET 8.0 installed on Mac OS, Microsoft.AspNetCore.SignalR.Protocols.MessagePack on....

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. Updated by Microsoft Security Response Center

    The vendor changed the advisory after it was first published.

  4. Confirmed at the source

    Our collector saw this advisory during a later source check.

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