Vulnerability Database

405,872

Total vulnerabilities in the database

CVE-2026-111768 — @modelcontextprotocol / sdk

Allocation of Resources Without Limits or Throttling

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.

CVSS v3:

  • Severity: High
  • Score: 7.5
  • AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CWEs:

Is CVE-2026-111768 exposed on your perimeter?

A vulnerability database tells you what is broken. Attack surface management tells you where it is running: it discovers your internet-facing assets and flags the ones affected by issues like this one.

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Frequently Asked Questions

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.

Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.

Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.

SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.