{"id":"GHSA-353c-v8x9-v7c3","summary":"MCP-Framework: Unbounded memory allocation in readRequestBody allows denial of service via HTTP transport","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 = '';\n      req.on('data', (chunk) =\u003e {\n        body += chunk.toString();   // No size limit\n      });\n      req.on('end', () =\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('error', 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 = '';\n      let size = 0;\n      req.on('data', (chunk) =\u003e {\n        size += chunk.length;\n        if (size \u003e maxSize) {\n          req.destroy();\n          reject(new Error('Request body too large'));\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)","aliases":["CVE-2026-39313"],"modified":"2026-05-05T15:59:44.086328Z","published":"2026-04-16T20:44:32Z","database_specific":{"github_reviewed_at":"2026-04-16T20:44:32Z","nvd_published_at":"2026-04-16T22:16:38Z","cwe_ids":["CWE-770"],"severity":"HIGH","github_reviewed":true},"references":[{"type":"WEB","url":"https://github.com/QuantGeekDev/mcp-framework/security/advisories/GHSA-353c-v8x9-v7c3"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-39313"},{"type":"WEB","url":"https://github.com/QuantGeekDev/mcp-framework/commit/f97d2bb76d6359faf10cd1fc54b4911476b62524"},{"type":"PACKAGE","url":"https://github.com/QuantGeekDev/mcp-framework"}],"affected":[{"package":{"name":"mcp-framework","ecosystem":"npm","purl":"pkg:npm/mcp-framework"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"0.2.22"}]}],"database_specific":{"last_known_affected_version_range":"\u003c= 0.2.21","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/04/GHSA-353c-v8x9-v7c3/GHSA-353c-v8x9-v7c3.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","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"}]}