GHSA-353C-V8X9-V7C3
Vulnerability from github – Published: 2026-04-16 20:44 – Updated: 2026-04-24 20:36
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
{
"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": "2026-04-16T22:16:38Z",
"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": "2026-04-24T20:36:27Z",
"published": "2026-04-16T20:44:32Z",
"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"
}
],
"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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|---|
Nomenclature
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vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
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They have not been verified by an analyst and are provided for guidance only.
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Browse all ATT&CK techniques and the vulnerabilities related to each.
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