MCP TypeScript SDK: One HTTP request within the default size limit could exhaust server memory during validation

{
  "id": "d56ca15821f9265dab31b1981a7b7a65ea67d46bfd785c162821e778ca498d43",
  "url": "https://osv.dev/vulnerability/GHSA-46jr-4wx8-v453",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "MCP TypeScript SDK: One HTTP request within the default size limit could exhaust server memory during validation",
    "summary": "### Summary In affected versions, servers put no limit on how many array elements and object keys they validated in one request. One HTTP request within the default 4 MiB size limit could exhaust the server's memory, and the process aborted with `JavaScript heap out of memory`. No credentials are needed, unless you authenticate requests before they reach the SDK. ### Am I affected? Yes, if clients you do not fully trust can reach your server over HTTP. The risk is highest for `McpServer` tools whose input contains an array or a record. stdio-only servers are not affected. Affected versions: - `@modelcontextprotocol/sdk` 1.3.0 through 1.31.0 - `@modelcontextprotocol/server` 2.0.0 through 2.2.0 ### Fix Upgrade to: - 1.x: `@modelcontextprotocol/sdk` 1.32.0 or later - 2.x: `@modelcontextprotocol/server` 2.3.0 or later **Upgrading alone changes nothing.** The patched versions add an `McpServer` option, `maxToolInputElements`, that is off by default. Make both of these changes: 1. Set `maxToolInputElements` just above the largest input your tools need, for example `new McpServer(info, { maxToolInputElements: 10_000 })`. It counts array elements and object keys in a call's arguments. A call over the limit gets an `isError: true` result. 2. Lower the request size limit to what your tools need. The option covers tool arguments only, and the size limit covers everything else. Set `maxRequestBodySize` on the transport or `createMcpHandler()`. If you parse the body yourself, for example ",
    "evidence": "osv:GHSA-46jr-4wx8-v453",
    "products": [
      {
        "name": {
          "value": "@modelcontextprotocol/sdk",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1.32.0",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "@modelcontextprotocol/server",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "2.3.0",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "GHSA-46jr-4wx8-v453",
      "aliases": [
        "CVE-2026-111768",
        "GHSA-46jr-4wx8-v453"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "1.3.0"
                },
                {
                  "fixed": "1.32.0"
                }
              ]
            }
          ],
          "package": {
            "name": "@modelcontextprotocol/sdk",
            "purl": "pkg:npm/%40modelcontextprotocol/sdk",
            "ecosystem": "npm"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-46jr-4wx8-v453/GHSA-46jr-4wx8-v453.json"
          }
        },
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "2.0.0"
                },
                {
                  "fixed": "2.3.0"
                }
              ]
            }
          ],
          "package": {
            "name": "@modelcontextprotocol/server",
            "purl": "pkg:npm/%40modelcontextprotocol/server",
            "ecosystem": "npm"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-46jr-4wx8-v453/GHSA-46jr-4wx8-v453.json"
          }
        }
      ],
      "modified": "2026-10-20T20:15:05.222078887Z",
      "provider": "osv",
      "references": [
        "https://github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-46jr-4wx8-v453",
        "https://github.com/modelcontextprotocol/typescript-sdk/pull/2926",
        "https://github.com/modelcontextprotocol/typescript-sdk/pull/2927",
        "https://github.com/modelcontextprotocol/typescript-sdk/commit/6d8dbc6cb590edf766fcb66b636ca6b654e99c37",
        "https://github.com/modelcontextprotocol/typescript-sdk/commit/fd26801b3b387742fe24a90ed4b275dd6072209f",
        "https://github.com/modelcontextprotocol/typescript-sdk"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-770"
        ],
        "severity": "HIGH",
        "github_reviewed": true,
        "nvd_published_at": null,
        "github_reviewed_at": "2026-10-20T20:06:35Z"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-111768",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/database_specific/severity"
  },
  "source_id": "core-osv",
  "document_id": 390366,
  "published_at": "2026-10-20T20:06:35+00:00"
}