Vulnerability · Published Jul 31, 2026 · Assigned by Google
CVE-2026-14539Denial of Service via Unrestricted Payload Buffering in MCP Toolbox
Medium 6.6
In plain English
A medium-severity resource allocation without limits in mcp-toolbox from Google. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 15% of all known vulnerabilities).
Official description
An allocation of resources without limits vulnerability in the HTTP handler component of Google mcp-toolbox versions up to and including 1.4.0 allows an unauthenticated attacker to cause a denial of service (DoS). The /mcp endpoint handler reads incoming payloads directly into system memory using an unrestricted buffer loop (io.ReadAll) without applying defensive constraints such as http.MaxBytesReader or pre-read Content-Length enforcement. By submitting a single, massive HTTP request body, an attacker can linearly consume available host memory until the runtime process is terminated by an Out-Of-Memory (OOM) error.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| mcp-toolbox | 0.0.0 – through 1.4.0 |
Weakness: CWE-770 · 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:U