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.
{
"cna_assigner": "GitHub_M",
"cwe_ids": [
"CWE-770"
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/39xxx/CVE-2026-39313.json"
}{
"extracted_events": [
{
"range": [
{
"introduced": "0"
},
{
"fixed": "0.2.22"
}
],
"source": "AFFECTED_FIELD",
"strategy": "StringRangeExpression"
},
{
"range": [
{
"fixed": "f97d2bb76d6359faf10cd1fc54b4911476b62524"
}
],
"source": "REFERENCES_COMMIT"
}
]
}