Answer in brief
CVE-2026-111768 records a High severity (CVSS 7.5) vulnerability in MCP TypeScript SDK: One HTTP request within the default size limit could exhaust server memory during validation. The current sources do not mark it as known exploited. The current feed maps @modelcontextprotocol/sdk (npm), @modelcontextprotocol/server (npm). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 7.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps @modelcontextprotocol/sdk (npm), @modelcontextprotocol/server (npm). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| @modelcontextprotocol/sdknpm | >=1.3.0,<1.32.0 | 1.32.0 |
| @modelcontextprotocol/servernpm | >=2.0.0,<2.3.0 | 2.3.0 |
Published upstream
Oct 20, 2026
Evidence: source:ghsa:source_dates:source-dates:recordSource modified
Oct 20, 2026
Evidence: source:ghsa:source_dates:source-dates:recordFirst seen by HOL
Oct 20, 2026
### 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 with `express.json()` or Fastify, set that parser's limit. If 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.
Quoted source text, attributed separately from HOL analysis.