CVE-2026-39313 MCP-Framework: Unbounded memory allocation in readRequestBody allows denial of service via HTTP transport
Remote attackers can crash MCP servers by sending large HTTP requests due to unbounded memory allocation in the readRequestBody function.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-39313?
CVE-2026-39313 is a high-severity denial of service vulnerability in QuantGeekDev mcp-framework, published on 16 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-770
Which versions are affected by CVE-2026-39313?
2 open source packages ship an affected version, including mcp-framework.
| Package | Affected | Fixed in |
|---|---|---|
mcp-framework npm | All versions | 0.2.22 |
mcp-framework npm | All versions | 0.2.22 |
How do I fix CVE-2026-39313?
Upgrade mcp-framework to 0.2.22 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-39313 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-39313 exists.
Sources
Also known as GHSA-353c-v8x9-v7c3.