8.7

CVSS Score

4.0

-

CVSS Score

Basic Information

Concerned about an active attack path?

Talk to our security experts and see Miggo in action.

Miggo Vulnerability Database

→

CVE-2026-39313

CVE-2026-39313: MCP-Framework: Unbounded memory allocation in readRequestBody allows denial of service via HTTP transport

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.

(GitHub Advisory)

Miggo Vulnerability Database

→

CVE-2026-39313

CVE-2026-39313:

8.7

CVSS Score

4.0

-

CVSS Score

Basic Information

Is this CVE running in your environment?

Easily map the attack path and prioritize which CVEs are a threat to your organization

Validate Exposure

Technical Details

Package Name	Ecosystem	Vulnerable Versions	First Patched Version
mcp-framework	npm	<= 0.2.21	0.2.22

Technical Details

Vulnerability Intelligence
Miggo AI

Root Cause Analysis

The vulnerability is a classic case of unbounded resource allocation (CWE-770). The readRequestBody function in src/transports/http/server.ts processes incoming HTTP request bodies. The original implementation concatenated incoming data chunks into a string variable (body) without any checks on the total size. This allows a remote, unauthenticated attacker to send a single, large POST request, causing the server to exhaust its memory and crash. The fix, as seen in commit f97d2bb76d6359faf10cd1fc54b4911476b62524, introduces a size check that enforces the maxMessageSize configuration, effectively mitigating the denial-of-service vulnerability. The vulnerable function is clearly HttpStreamTransport.readRequestBody as it is the function that was modified to add the necessary security control.

Vulnerable functions

HttpStreamTransport.readRequestBody

src/transports/http/server.ts

The function `readRequestBody` within the `HttpStreamTransport` class is responsible for reading the body of an incoming HTTP request. The vulnerability lies in the fact that it reads the entire request body into memory without enforcing any size limits. An attacker could exploit this by sending a request with a very large body, causing the server to allocate an unbounded amount of memory, which could lead to a denial of service by crashing the application.

Vulnerability Intelligence
Miggo AI

Unlock WAF rules for this CVE

Generate vendor-ready rules for the observed attack patterns, plus reasoning and safe deployment guidance

Get WAF rules

WAF Protection Rules

WAF Rule

W** rul*s *v*il**l* *or Mi**o *ustom*rs only.W** rul*s *v*il**l* *or Mi**o *ustom*rs only.W** rul*s *v*il**l* *or Mi**o *ustom*rs only.W** rul*s *v*il**l* *or Mi**o *ustom*rs only.W** rul*s *v*il**l* *or Mi**o *ustom*rs only.W** rul*s *v*il**l* *or Mi**o *ustom*rs only.W** rul*s *v*il**l* *or Mi**o *ustom*rs only.W** rul*s *v*il**l* *or Mi**o *ustom*rs only.W** rul*s *v*il**l* *or Mi**o *ustom*rs only.W** rul*s *v*il**l* *or Mi**o *ustom*rs only.

Reasoning

*v*il**l* *or Mi**o *ustom*rs only.*v*il**l* *or Mi**o *ustom*rs only.*v*il**l* *or Mi**o *ustom*rs only.*v*il**l* *or Mi**o *ustom*rs only.*v*il**l* *or Mi**o *ustom*rs only.*v*il**l* *or Mi**o *ustom*rs only.*v*il**l* *or Mi**o *ustom*rs only.*v*il**l* *or Mi**o *ustom*rs only.*v*il**l* *or Mi**o *ustom*rs only.*v*il**l* *or Mi**o *ustom*rs only.