Microsoft Security Advisory CVE-2026-92707 - ASP.NET Core Denial of Service Vulnerability

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Executive summary Microsoft is releasing this security advisory to provide information about a vulnerability in Microsoft.AspNetCore.SignalR.Protocols.MessagePack; MessagePack; MessagePack.Annotations; MessagePackAnalyzer. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability. SignalR's MessagePack protocol can consume excessive memory while deserializing deeply nested attacker-controlled arrays, resulting in unauthenticated remote denial of service. Announcement Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/473 CVSS Details - Version: 3.1 - Severity: Moderate - Score: 5.3 - Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L - Weakness: CWE-1325 (Improperly Controlled Sequential Memory Allocation) Affected Platforms - Platforms: Windows, Linux, macOS - Architectures: All <a name="affected-packages"</aAffected Packages The vulnerability affects Microsoft .NET projects that…

Published by the source

13 Oct 2026, 20:11 UTC

Last modified by the source

13 Oct 2026, 20:30 UTC

Source last checked

26 Oct 2026, 17:05 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-86xp-94pg-8r6r

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-86xp-94pg-8r6r

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# Patch Next advisory brief: GHSA-86xp-94pg-8r6r

Advisory: Microsoft Security Advisory CVE-2026-92707 - ASP.NET Core Denial of Service Vulnerability
IDs: GHSA-86xp-94pg-8r6r
Record: https://patchnext.com/advisories/ghsa-86xp-94pg-8r6r (revision 2, source checked 26 Oct 2026, 17:05 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: microsoft.aspnetcore.signalr.protocols.messagepack 11.0.0-rc.2, 10.0.13, 9.0.21, 8.0.32. A vendor fix does not mean a deployment is fixed.

## Affected components
- NuGet microsoft.aspnetcore.signalr.protocols.messagepack: affected >= 10.0.0, <= 10.0.12; >= 11.0.0-preview.5, <= 11.0.0-rc.1; >= 8.0.0, <= 8.0.31; >= 9.0.0, <= 9.0.20; fixed in 11.0.0-rc.2, 10.0.13, 8.0.32, 9.0.21

## Suggested inspection (read-only)
- NuGet microsoft.aspnetcore.signalr.protocols.messagepack: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on microsoft.aspnetcore.signalr.protocols.messagepack.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-86xp-94pg-8r6r (OSV record GHSA-86xp-94pg-8r6r lists affected ranges: NuGet microsoft.aspnetcore.signalr.protocols.messagepack >=10.0.0 =11.0.0-preview.5 =8.0.0 =9.0.0 <9.0.21 (fixed))
- Verified: https://github.com/advisories/GHSA-86xp-94pg-8r6r (GitHub-reviewed advisory GHSA-86xp-94pg-8r6r lists affected ranges: NuGet microsoft.aspnetcore.signalr.protocols.messagepack >=10.0.0 =11.0.0-preview.5 =8.0.0 =9.0.0 <=9.0.20)

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