{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "cpe": "cpe:2.3:a:messagepack:messagepack:*:*:*:*:*:c\\#:*:*",
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "2.5.301"
              },
              {
                "introduced": "3.0.3"
              },
              {
                "fixed": "3.1.7"
              }
            ],
            "source": "CPE_RANGE"
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "5657b1e34ea2869a2ca6bc0aa6617158620201ba"
            },
            {
              "introduced": "ff3af77f546138d9da71707baddf2c30f55dfc15"
            },
            {
              "fixed": "1b53ae8b7681340199faf337bcbb0eb5aed702de"
            }
          ],
          "repo": "https://github.com/messagepack-csharp/messagepack-csharp",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-cxmj-83gh-fp49"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-770"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/48xxx/CVE-2026-48515.json"
  },
  "details": "MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, MessagePack-CSharp's multi-dimensional array formatters read dimension lengths directly from the payload and allocate T[,], T[,,], or T[,,,] before validating that the dimension product matches the encoded element count. The formatter reads a guarded element array header, but allocation of the target multi-dimensional array happens before the dimensions are checked against that element count. A small payload can therefore declare large dimensions, provide an empty or tiny inner array, and cause a large heap allocation before element data is validated. This vulnerability is fixed in 2.5.301 and 3.1.7.",
  "id": "CVE-2026-48515",
  "modified": "2026-08-27T03:31:03.732993625Z",
  "published": "2026-06-22T21:10:39.110Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/48xxx/CVE-2026-48515.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/MessagePack-CSharp/MessagePack-CSharp/security/advisories/GHSA-cxmj-83gh-fp49"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-48515"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "MessagePack-CSharp: Multi-dimensional array formatters allocate from unchecked dimensions"
}