GHSA-353C-V8X9-V7C3

Vulnerability from github – Published: 2026-04-16 20:44 – Updated: 2026-04-16 20:44
VLAI?
Summary
MCP-Framework: Unbounded memory allocation in readRequestBody allows denial of service via HTTP transport
Details

Summary

The readRequestBody() function in src/transports/http/server.ts concatenates HTTP request body chunks into a string with no size limit, allowing a remote unauthenticated attacker to crash the server via memory exhaustion with a single large HTTP POST request.

Details

File: src/transports/http/server.ts, lines 224-240

private async readRequestBody(req: IncomingMessage): Promise<any> {
    return new Promise((resolve, reject) => {
      let body = '';
      req.on('data', (chunk) => {
        body += chunk.toString();   // No size limit
      });
      req.on('end', () => {
        try {
          const parsed = body ? JSON.parse(body) : null;
          resolve(parsed);
        } catch (error) {
          reject(error);
        }
      });
      req.on('error', reject);
    });
  }

A maxMessageSize configuration value exists in DEFAULT_HTTP_STREAM_CONFIG (4MB, defined in src/transports/http/types.ts line 124) but is never enforced in readRequestBody(). This creates a false sense of security.

PoC

Local testing with 50MB POST payloads against the vulnerable readRequestBody() function:

Trial Payload RSS growth Time Result
1 50MB +197MB 42ms Vulnerable
2 50MB +183MB 46ms Vulnerable
3 50MB +15MB 43ms Vulnerable
4 50MB +14MB 32ms Vulnerable
5 50MB +65MB 38ms Vulnerable

Reproducibility: 5/5 (100%)

Impact

  • Denial of Service: Any mcp-framework HTTP server can be crashed by a single large POST request to /mcp
  • No authentication required: readRequestBody() executes before any auth checks (auth is opt-in, default is no auth)
  • Dead config: maxMessageSize exists but is never enforced, giving a false sense of security
  • Affected: All applications using mcp-framework HttpStreamTransport (60,000 weekly npm downloads)

CWE-770: Allocation of Resources Without Limits or Throttling Suggested CVSS 3.1: 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)

Suggested Fix

Enforce maxMessageSize in readRequestBody():

private async readRequestBody(req: IncomingMessage): Promise<any> {
    const maxSize = this._config.maxMessageSize || 4 * 1024 * 1024;
    return new Promise((resolve, reject) => {
      let body = '';
      let size = 0;
      req.on('data', (chunk) => {
        size += chunk.length;
        if (size > maxSize) {
          req.destroy();
          reject(new Error('Request body too large'));
          return;
        }
        body += chunk.toString();
      });
      // ...
    });
  }

Disclosure Timeline

This report follows coordinated disclosure. I request a 90-day window before public disclosure.

Reporter: Raza Sharif, CyberSecAI Ltd (contact@agentsign.dev)

Severity ?
8.7 (High)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Show details on source website
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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 0.2.21"
      },
      "package": {
        "ecosystem": "npm",
        "name": "mcp-framework"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.2.22"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-39313"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-770"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-16T20:44:32Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "### Summary\n\nThe `readRequestBody()` function in `src/transports/http/server.ts` concatenates HTTP request body chunks into a string with no size limit, allowing a remote unauthenticated attacker to crash the server via memory exhaustion with a single large HTTP POST request.\n\n### Details\n\n**File:** `src/transports/http/server.ts`, lines 224-240\n\n```typescript\nprivate async readRequestBody(req: IncomingMessage): Promise\u003cany\u003e {\n    return new Promise((resolve, reject) =\u003e {\n      let body = \u0027\u0027;\n      req.on(\u0027data\u0027, (chunk) =\u003e {\n        body += chunk.toString();   // No size limit\n      });\n      req.on(\u0027end\u0027, () =\u003e {\n        try {\n          const parsed = body ? JSON.parse(body) : null;\n          resolve(parsed);\n        } catch (error) {\n          reject(error);\n        }\n      });\n      req.on(\u0027error\u0027, reject);\n    });\n  }\n```\n\nA `maxMessageSize` configuration value exists in `DEFAULT_HTTP_STREAM_CONFIG` (4MB, defined in `src/transports/http/types.ts` line 124) but is never enforced in `readRequestBody()`. This creates a false sense of security.\n\n### PoC\n\nLocal testing with 50MB POST payloads against the vulnerable `readRequestBody()` function:\n\n| Trial | Payload | RSS growth | Time | Result |\n|-------|---------|-----------|------|--------|\n| 1 | 50MB | +197MB | 42ms | Vulnerable |\n| 2 | 50MB | +183MB | 46ms | Vulnerable |\n| 3 | 50MB | +15MB | 43ms | Vulnerable |\n| 4 | 50MB | +14MB | 32ms | Vulnerable |\n| 5 | 50MB | +65MB | 38ms | Vulnerable |\n\nReproducibility: 5/5 (100%)\n\n### Impact\n\n- **Denial of Service:** Any mcp-framework HTTP server can be crashed by a single large POST request to /mcp\n- **No authentication required:** readRequestBody() executes before any auth checks (auth is opt-in, default is no auth)\n- **Dead config:** maxMessageSize exists but is never enforced, giving a false sense of security\n- **Affected:** All applications using mcp-framework HttpStreamTransport (60,000 weekly npm downloads)\n\n**CWE-770:** Allocation of Resources Without Limits or Throttling\n**Suggested CVSS 3.1:** 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)\n\n### Suggested Fix\n\nEnforce `maxMessageSize` in `readRequestBody()`:\n\n```typescript\nprivate async readRequestBody(req: IncomingMessage): Promise\u003cany\u003e {\n    const maxSize = this._config.maxMessageSize || 4 * 1024 * 1024;\n    return new Promise((resolve, reject) =\u003e {\n      let body = \u0027\u0027;\n      let size = 0;\n      req.on(\u0027data\u0027, (chunk) =\u003e {\n        size += chunk.length;\n        if (size \u003e maxSize) {\n          req.destroy();\n          reject(new Error(\u0027Request body too large\u0027));\n          return;\n        }\n        body += chunk.toString();\n      });\n      // ...\n    });\n  }\n```\n\n### Disclosure Timeline\n\nThis report follows coordinated disclosure. I request a 90-day window before public disclosure.\n\n**Reporter:** Raza Sharif, CyberSecAI Ltd (contact@agentsign.dev)",
  "id": "GHSA-353c-v8x9-v7c3",
  "modified": "2026-04-16T20:44:32Z",
  "published": "2026-04-16T20:44:32Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/QuantGeekDev/mcp-framework/security/advisories/GHSA-353c-v8x9-v7c3"
    },
    {
      "type": "WEB",
      "url": "https://github.com/QuantGeekDev/mcp-framework/commit/f97d2bb76d6359faf10cd1fc54b4911476b62524"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/QuantGeekDev/mcp-framework"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "MCP-Framework: Unbounded memory allocation in readRequestBody allows denial of service via HTTP transport"
}


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  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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