{"id":"CVE-2026-111768","aliases":["GHSA-46jr-4wx8-v453"],"title":"MCP TypeScript SDK: One HTTP request within the default size limit could exhaust server memory during validation","summary":"MCP TypeScript SDK: One HTTP request within the default size limit could exhaust server memory during validation","severity":"high","cvss":7.5,"cwe":["CWE-770"],"vendor":"modelcontextprotocol","product":"@modelcontextprotocol/sdk","ecosystem":"npm","affected":["@modelcontextprotocol/sdk >= 1.3.0, < 1.32.0","@modelcontextprotocol/server >= 2.0.0, < 2.3.0"],"patched":["@modelcontextprotocol/sdk 1.32.0","@modelcontextprotocol/server 2.3.0"],"published":"2026-10-20","updated":"2026-10-20","sourceUpdated":"2026-10-20T20:06:38Z","source":"GHSA","sourceUrl":"https://github.com/advisories/GHSA-46jr-4wx8-v453","references":[{"url":"https://github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-46jr-4wx8-v453"},{"url":"https://github.com/modelcontextprotocol/typescript-sdk/pull/2926"},{"url":"https://github.com/modelcontextprotocol/typescript-sdk/pull/2927"},{"url":"https://github.com/modelcontextprotocol/typescript-sdk/commit/6d8dbc6cb590edf766fcb66b636ca6b654e99c37"},{"url":"https://github.com/modelcontextprotocol/typescript-sdk/commit/fd26801b3b387742fe24a90ed4b275dd6072209f"},{"url":"https://github.com/advisories/GHSA-46jr-4wx8-v453"}],"tags":["ghsa","npm"],"ingestedAt":"2026-10-20T20:18:14.522Z","slug":"CVE-2026-111768","body":"## Overview\n\n### Summary\nIn 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`.\n\nNo credentials are needed, unless you authenticate requests before they reach the SDK.\n\n### Am I affected?\nYes, 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.\n\nAffected versions:\n\n- `@modelcontextprotocol/sdk` 1.3.0 through 1.31.0\n- `@modelcontextprotocol/server` 2.0.0 through 2.2.0\n\n### Fix\nUpgrade to:\n\n- 1.x: `@modelcontextprotocol/sdk` 1.32.0 or later\n- 2.x: `@modelcontextprotocol/server` 2.3.0 or later\n\n**Upgrading alone changes nothing.** The patched versions add an `McpServer` option, `maxToolInputElements`, that is off by default. Make both of these changes:\n\n1. 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.\n2. 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 with `express.json()` or Fastify, set that parser's limit.\n\nIf you cannot upgrade yet, make the second change. `maxRequestBodySize` needs `@modelcontextprotocol/sdk` 1.30.1 or `@modelcontextprotocol/server` 2.1.0. Below that, use a reverse proxy.\n\n## Affected packages\n\n- `@modelcontextprotocol/sdk >= 1.3.0, < 1.32.0`\n- `@modelcontextprotocol/server >= 2.0.0, < 2.3.0`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `@modelcontextprotocol/sdk 1.32.0`\n- `@modelcontextprotocol/server 2.3.0`","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}