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msgpack5: Quadratic parsing in the streaming decoder

Type: advisorySources: OSV

msgpack5 is a msgpack v5 implementation for node.js and the browser. Prior to 6.1.0, the streaming decoder reparses an incomplete array or map from the beginning whenever another chunk arrives. A remote peer can split one valid MessagePack container across many small chunks, causing completed elements to be decoded repeatedly, producing quadratic CPU use and blocking the event loop. This issue is fixed in version 6.1.0.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2026-107297
Confirmed fixed CVEs
Not specified
Updated in this feed
3 Nov 2026, 16:49 UTC · Revision 1

Source evidence

msgpack5: Quadratic parsing in the streaming decoder

core-osv · Original source

Published 8 Oct 2026, 17:07 UTC

msgpack5 is a msgpack v5 implementation for node.js and the browser. Prior to 6.1.0, the streaming decoder reparses an incomplete array or map from the beginning whenever another chunk arrives. A remote peer can split one valid MessagePack container across many small chunks, causing completed elements to be decoded repeatedly, producing quadratic CPU use and blocking the event loop. This issue is fixed in version 6.1.0.

osv:CVE-2026-107297
Complete source record
{
  "id": "bd499cba9ebe1db4e610dbd9caf7061913a73934729cf106584afcc3c199a7e9",
  "url": "https://osv.dev/vulnerability/CVE-2026-107297",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "msgpack5: Quadratic parsing in the streaming decoder",
    "summary": "msgpack5 is a msgpack v5 implementation for node.js and the browser. Prior to 6.1.0, the streaming decoder reparses an incomplete array or map from the beginning whenever another chunk arrives. A remote peer can split one valid MessagePack container across many small chunks, causing completed elements to be decoded repeatedly, producing quadratic CPU use and blocking the event loop. This issue is fixed in version 6.1.0.",
    "evidence": "osv:CVE-2026-107297",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-107297",
      "aliases": [
        "CVE-2026-107297",
        "GHSA-gcx5-hxj7-gpqq"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/mcollina/msgpack5",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "3730a5a754ec06912e42865eed9489ed64238ecb"
                },
                {
                  "fixed": "e4827641d3105e295cbbd56e9c5389978547eab4"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "6.1.0"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "fixed": "e4827641d3105e295cbbd56e9c5389978547eab4"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "3730a5a754ec06912e42865eed9489ed64238ecb"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v6.1.0"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v6.0.2",
            "v6.0.0",
            "v5.3.2",
            "v5.3.1",
            "v3.6.1",
            "v3.6.0",
            "v5.3.0",
            "v5.2.1",
            "v5.2.0",
            "v5.1.0",
            "v5.0.0",
            "v4.4.0",
            "v4.3.0",
            "v4.2.0",
            "v4.1.0",
            "v4.0.2",
            "v4.0.1",
            "v4.0.0",
            "v3.5.0",
            "v3.4.1",
            "v3.4.0",
            "v3.3.0",
            "v3.2.0",
            "v3.1.0",
            "v3.0.0",
            "v2.3.1",
            "v2.3.0",
            "v2.2.0",
            "v2.1.0",
            "v2.0.0",
            "v1.6.0",
            "v1.5.0",
            "v1.3.2",
            "v1.3.1",
            "v1.2.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-107297.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:30.700604535Z",
      "provider": "osv",
      "references": [
        "https://github.com/mcollina/msgpack5/releases/tag/v6.1.0",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/107xxx/CVE-2026-107297.json",
        "https://github.com/mcollina/msgpack5/security/advisories/GHSA-gcx5-hxj7-gpqq",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-107297",
        "https://github.com/mcollina/msgpack5/commit/e4827641d3105e295cbbd56e9c5389978547eab4"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-407"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/107xxx/CVE-2026-107297.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-107297",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 497602,
  "published_at": "2026-10-08T17:07:03.74+00:00"
}