{"id":"CVE-2026-92707","title":"MessagePack for C# is a MessagePack serializer for C#","summary":"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 …","severity":"medium","cvss":5.3,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","cwe":["CWE-1325","CWE-770"],"vendor":"MessagePack","product":"MessagePack","affected":["MessagePack < 2.5.303","MessagePack >= 3.0.0, < 3.1.9"],"patched":["MessagePack 2.5.303","MessagePack 3.1.9"],"published":"2026-10-15","updated":"2026-10-16","sourceUpdated":"2026-10-16T16:00:33.533","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-92707","references":[{"url":"https://github.com/MessagePack-CSharp/MessagePack-CSharp/commit/7fd78bbf3476e03beae8b0f7a521125525a8a64a","label":"security-advisories@github.com"},{"url":"https://github.com/MessagePack-CSharp/MessagePack-CSharp/commit/95b63fca4f7097d3cac12d1a95286af4b4bbf02c","label":"security-advisories@github.com"},{"url":"https://github.com/MessagePack-CSharp/MessagePack-CSharp/releases/tag/v2.5.303","label":"security-advisories@github.com"},{"url":"https://github.com/MessagePack-CSharp/MessagePack-CSharp/releases/tag/v3.1.9","label":"security-advisories@github.com"},{"url":"https://github.com/MessagePack-CSharp/MessagePack-CSharp/security/advisories/GHSA-qhrr-8q5h-9q3h","label":"security-advisories@github.com"},{"url":"https://github.com/advisories/GHSA-qhrr-8q5h-9q3h"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-92707.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-92707"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2548800"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-92707"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-92707"},{"url":"https://access.redhat.com/errata/RHSA-2026:86195"},{"url":"https://access.redhat.com/errata/RHSA-2026:86168"},{"url":"https://access.redhat.com/errata/RHSA-2026:86172"},{"url":"https://access.redhat.com/errata/RHSA-2026:86192"},{"url":"https://access.redhat.com/errata/RHSA-2026:86594"},{"url":"https://access.redhat.com/errata/RHSA-2026:86170"},{"url":"https://access.redhat.com/errata/RHSA-2026:86193"},{"url":"https://access.redhat.com/errata/RHSA-2026:86169"},{"url":"https://access.redhat.com/errata/RHSA-2026:86171"},{"url":"https://access.redhat.com/errata/RHSA-2026:88474"},{"url":"https://access.redhat.com/errata/RHSA-2026:88424"},{"url":"https://access.redhat.com/errata/RHSA-2026:88425"},{"url":"https://access.redhat.com/errata/RHSA-2026:88422"}],"tags":["nvd","ghsa","nuget","cve.org","csaf","vex","red-hat"],"epss":0.00678,"epssPercentile":0.52124,"aliases":["GHSA-qhrr-8q5h-9q3h"],"ecosystem":"nuget","ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"partial","timestamp":"2026-10-15T20:10:28.719217Z"},"ingestedAt":"2026-10-15T19:25:46.438Z","slug":"CVE-2026-92707","body":"## Overview\n\nMessagePack 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Package advisory (CVE-2026-92707)\n\nAffected packages:\n\n- `MessagePack < 2.5.303`\n- `MessagePack >= 3.0.0, < 3.1.9`\n\nPatched in:\n\n- `MessagePack 2.5.303`\n- `MessagePack 3.1.9`\n\nSource: https://github.com/advisories/GHSA-qhrr-8q5h-9q3h\n\n## Vendor advisories\n\n- **RHSA-2026:86195** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) · released 2026-10-20 · [advisory](https://access.redhat.com/errata/RHSA-2026:86195)\n- **RHSA-2026:86168** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) · released 2026-10-20 · [advisory](https://access.redhat.com/errata/RHSA-2026:86168)\n- **RHSA-2026:86172** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) · released 2026-10-20 · [advisory](https://access.redhat.com/errata/RHSA-2026:86172)\n- **RHSA-2026:86192** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 8), Red Hat Enterprise Linux CRB (v. 8) · released 2026-10-20 · [advisory](https://access.redhat.com/errata/RHSA-2026:86192)\n- **RHSA-2026:86594** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 8), Red Hat Enterprise Linux CRB (v. 8) · released 2026-10-21 · [advisory](https://access.redhat.com/errata/RHSA-2026:86594)\n- **RHSA-2026:86170** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 8), Red Hat Enterprise Linux CRB (v. 8) · released 2026-10-20 · [advisory](https://access.redhat.com/errata/RHSA-2026:86170)\n- **RHSA-2026:86193** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) · released 2026-10-20 · [advisory](https://access.redhat.com/errata/RHSA-2026:86193)\n- **RHSA-2026:86169** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) · released 2026-10-20 · [advisory](https://access.redhat.com/errata/RHSA-2026:86169)\n- **RHSA-2026:86171** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) · released 2026-10-20 · [advisory](https://access.redhat.com/errata/RHSA-2026:86171)\n- **RHSA-2026:88474** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream EUS (v. 10.0), Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) · released 2026-10-22 · [advisory](https://access.redhat.com/errata/RHSA-2026:88474)\n- **RHSA-2026:88424** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream EUS (v. 10.0), Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) · released 2026-10-22 · [advisory](https://access.redhat.com/errata/RHSA-2026:88424)\n- **RHSA-2026:88425** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream E4S (v.9.4) · released 2026-10-22 · [advisory](https://access.redhat.com/errata/RHSA-2026:88425)\n- **RHSA-2026:88422** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream EUS (v.9.6), Red Hat CodeReady Linux Builder EUS (v.9.6) · released 2026-10-22 · [advisory](https://access.redhat.com/errata/RHSA-2026:88422)","depth":"sunlit","depthScore":29,"depthScoreParts":{"impact":29.2,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}