{"id":"CVE-2026-92707","revision":"bae9189fbf1d412b9f2d7c1665548ba4","records":[{"revision":"bae9189fbf1d412b9f2d7c1665548ba4","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-92707","aliases":[],"title":"MessagePack: Nested arrays can blow past buffer length limits","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.","state":0,"publishedAt":"2026-10-15T18:35:49.074+00:00","modifiedAt":"2026-10-15T20:12:15.468+00:00","affected":[{"ecosystem":"Vendor product","name":"MessagePack-CSharp","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"MessagePack-CSharp\",\n                    \"product\": \"MessagePack-CSharp\",\n                    \"versions\": [\n                        {\n                            \"version\": \"< 2.5.303\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \">= 3.0.0, < 3.1.9\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","score":5.3,"severity":"MEDIUM"}],"references":["https://github.com/MessagePack-CSharp/MessagePack-CSharp/security/advisories/GHSA-qhrr-8q5h-9q3h","https://github.com/MessagePack-CSharp/MessagePack-CSharp/commit/7fd78bbf3476e03beae8b0f7a521125525a8a64a","https://github.com/MessagePack-CSharp/MessagePack-CSharp/commit/95b63fca4f7097d3cac12d1a95286af4b4bbf02c","https://github.com/MessagePack-CSharp/MessagePack-CSharp/releases/tag/v2.5.303","https://github.com/MessagePack-CSharp/MessagePack-CSharp/releases/tag/v3.1.9"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-92707","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-92707","identifiers":["CVE-2026-92707"]},"retained":false,"historicalAffected":[]}],"coverage":[]}