CVE-2026-92707

CVE Details

Release Date:	2026-10-15
Impact:	Moderate	What is this?

Description

MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.303 and 3.1.9, deserializing attacker-controlled MessagePack data as System.Object through PrimitiveObjectFormatter can cause excessive memory allocation. The formatter allocates an object[] from each declared array length before the configured object-graph depth limit rejects the input, while nested array headers can reuse the same trailing unread bytes to satisfy per-header length validation. A comparatively small payload can therefore keep many large arrays alive at once. When an attacker can submit such data repeatedly, the allocations can cause severe managed-heap pressure, excessive garbage collection, process termination, or loss of service. Exposure requires an application to deserialize untrusted data through the affected formatter path and permit repeated attacker-controlled submissions, such as a reachable ASP.NET Core SignalR hub method with an object parameter and AddMessagePackProtocol() enabled. This issue is fixed in versions 2.5.303 and 3.1.9.

See more information about CVE-2026-92707 from MITRE CVE dictionary and NIST NVD

NOTE: The following CVSS metrics and score provided are preliminary and subject to review.

CVSS v3 metrics

Base Score:	5.3
Vector String:	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Version:	3.1
Attack Vector:	Network
Attack Complexity:	Low
Privileges Required:	None
User Interaction:	None
Scope:	Unchanged
Confidentiality Impact:	None
Integrity Impact:	None
Availability Impact:	Low

Errata information

Platform	Errata	Release Date
Oracle Linux version 10 (dotnet10.0)	ELSA-2026-86195	2026-10-21
Oracle Linux version 10 (dotnet9.0)	ELSA-2026-86172	2026-10-21
Oracle Linux version 9 (dotnet10.0)	ELSA-2026-86193	2026-10-21
Oracle Linux version 9 (dotnet8.0)	ELSA-2026-86169	2026-10-21
Oracle Linux version 9 (dotnet9.0)	ELSA-2026-86171	2026-10-21