MCP Ruby SDK: Unbounded JSON-RPC request body causes uncontrolled memory allocation in StreamableHTTPTransport

Date Jul 30, 2026

Type Vendor advisory

Signal High-risk advisory

Vendor / Product RubyGems · mcp

CVE CVE-2026-67432

High-risk advisory CVE-2026-67432

Summary

MCP Ruby SDK: Unbounded JSON-RPC request body causes uncontrolled memory allocation in StreamableHTTPTransport

Why it matters

GitHub has published a reviewed security advisory for mcp. Prioritize it with other application dependency updates, especially because EPSS places it in the 36% percentile.

Operator check

Check whether mcp is present in application dependency manifests, lockfiles, or build images. Review the GitHub advisory and upgrade to a patched version where available. EPSS probability: 0.4%; percentile: 36%.

Sources

GitHub Advisory GHSA-h669-8m4g-r2hc NVD — CVE-2026-67432 Source reference

PatchBrief uses public sources. It does not scan environments, verify exposure, or replace vendor guidance.

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