{"id":"CVE-2026-39313","aliases":["EUVD-2026-23300","GHSA-353c-v8x9-v7c3"],"status":"published","title":"MCP-Framework: Unbounded memory allocation in readRequestBody allows denial of service via HTTP transport","description":"mcp-framework is a framework for building Model Context Protocol (MCP) servers. In versions 0.2.21 and below, the readRequestBody() function in the HTTP transport concatenates request body chunks into a string with no size limit. Although a maxMessageSize configuration value exists, it is never enforced in readRequestBody(). A remote unauthenticated attacker can crash any mcp-framework HTTP server by sending a single large POST request to /mcp, causing memory exhaustion and denial of service. This issue has been fixed in version 0.2.22.","severity":{"version":"4.0","score":8.7,"vector":"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","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-09","score":0.00495,"percentile":0.42752,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-770"],"published":"2026-04-16T20:44:32Z","modified":"2026-10-28T02:31:06Z","fixes":[{"ecosystem":"npm","package":"mcp-framework","fixed_in":["0.2.22"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"npm","package":"mcp-framework","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"0.2.21"},{"fixed":"0.2.22"}]}]},{"source":"osv","ecosystem":"npm","package":"mcp-framework","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"0.2.22"}]}]}],"products":[{"vendor":"quantgeekdev","product":"mcp-framework"}],"references":[{"url":"https://github.com/QuantGeekDev/mcp-framework/security/advisories/GHSA-353c-v8x9-v7c3","tags":["x_refsource_CONFIRM","advisory","web"]},{"url":"https://github.com/QuantGeekDev/mcp-framework/commit/f97d2bb76d6359faf10cd1fc54b4911476b62524","tags":["x_refsource_MISC","fix","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-39313","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-353c-v8x9-v7c3"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/39xxx/CVE-2026-39313.json","tags":["advisory"]},{"url":"https://github.com/QuantGeekDev/mcp-framework","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-39313","title":"MCP-Framework: Unbounded memory allocation in readRequestBody allows denial of service via HTTP transport","description":"mcp-framework is a framework for building Model Context Protocol (MCP) servers. In versions 0.2.21 and below, the readRequestBody() function in the HTTP transport concatenates request body chunks into a string with no size limit. Although a maxMessageSize configuration value exists, it is never enforced in readRequestBody(). A remote unauthenticated attacker can crash any mcp-framework HTTP server by sending a single large POST request to /mcp, causing memory exhaustion and denial of service. This issue has been fixed in version 0.2.22.","status":"published","published":"2026-04-16T21:24:27.328Z","modified":"2026-04-17T18:46:07.726Z","cvss":[{"version":"4.0","score":8.7,"vector":"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","level":"high","assessor":"cna"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T14:20:02.662847Z"}],"euvd":[{"id":"EUVD-2026-23300","description":"mcp-framework is a framework for building Model Context Protocol (MCP) servers. In versions 0.2.21 and below, the readRequestBody() function in the HTTP transport concatenates request body chunks into a string with no size limit. Although a maxMessageSize configuration value exists, it is never enforced in readRequestBody(). A remote unauthenticated attacker can crash any mcp-framework HTTP server by sending a single large POST request to /mcp, causing memory exhaustion and denial of service. This issue has been fixed in version 0.2.22.","status":"published","published":"2026-04-16T21:24:27Z","modified":"2026-04-17T18:46:07Z","cvss":[{"version":"4.0","score":8.7,"vector":"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","level":"high"}],"updated_at":"2026-11-02T19:24:23.330761Z"}],"ghsa":[{"id":"GHSA-353c-v8x9-v7c3","title":"MCP-Framework: Unbounded memory allocation in readRequestBody allows denial of service via HTTP transport","description":"### 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)","status":"published","published":"2026-04-16T20:44:32Z","modified":"2026-04-24T20:36:28Z","cvss":[{"version":"4.0","score":8.7,"vector":"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","level":"high"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T14:39:56.453138Z"}],"nvd":[{"id":"CVE-2026-39313","description":"mcp-framework is a framework for building Model Context Protocol (MCP) servers. In versions 0.2.21 and below, the readRequestBody() function in the HTTP transport concatenates request body chunks into a string with no size limit. Although a maxMessageSize configuration value exists, it is never enforced in readRequestBody(). A remote unauthenticated attacker can crash any mcp-framework HTTP server by sending a single large POST request to /mcp, causing memory exhaustion and denial of service. This issue has been fixed in version 0.2.22.","status":"published","published":"2026-04-16T22:16:38.073Z","modified":"2026-10-26T21:10:00.17Z","cvss":[{"version":"4.0","score":8.7,"vector":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high","assessor":"secondary"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T14:12:15.120927Z"}],"osv":[{"id":"CVE-2026-39313","title":"MCP-Framework: Unbounded memory allocation in readRequestBody allows denial of service via HTTP transport","description":"mcp-framework is a framework for building Model Context Protocol (MCP) servers. In versions 0.2.21 and below, the readRequestBody() function in the HTTP transport concatenates request body chunks into a string with no size limit. Although a maxMessageSize configuration value exists, it is never enforced in readRequestBody(). A remote unauthenticated attacker can crash any mcp-framework HTTP server by sending a single large POST request to /mcp, causing memory exhaustion and denial of service. This issue has been fixed in version 0.2.22.","status":"published","published":"2026-04-16T21:24:27.328Z","modified":"2026-10-28T02:31:06.176010113Z","cvss":[{"version":"4.0","score":8.7,"vector":"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","level":"high"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T15:45:03.040464Z"},{"id":"GHSA-353c-v8x9-v7c3","title":"MCP-Framework: Unbounded memory allocation in readRequestBody allows denial of service via HTTP transport","description":"### 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)","status":"published","published":"2026-04-16T20:44:32Z","modified":"2026-05-05T15:59:44.086328Z","cvss":[{"version":"4.0","score":8.7,"vector":"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","level":"high"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T15:46:35.050232Z"}]}}