CVE-2026-14539 PUBLISHED

Denial of Service via Unrestricted Payload Buffering in MCP Toolbox

Assigner: Google
Reserved: 03.07.2026 Published: 31.07.2026 Updated: 31.07.2026

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.

Metrics

CVSS 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
CVSS Score: 6.6

Product Status

Vendor Google
Product mcp-toolbox
Versions Default: unaffected
  • affected from 0.0.0 to 1.4.0 (incl.)

Credits

  • HE WEI (ギカク) finder

References

Problem Types

  • CWE-770 (Allocation of Resources Without Limits or Throttling) CWE

Impacts

  • CAPEC-130 Excessive Allocation