What is CVE-2026-67432?

CVE-2026-67432 is a high-severity vulnerability in Modelcontextprotocol Ruby-Sdk, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 7.5/10. Published 2026-07-29.

How severe is CVE-2026-67432?

High severity. CVSS v3 base score is 7.5 out of 10.

Resource exhaustion in Modelcontextprotocol Ruby-Sdk

CVE-2026-67432

MCP Ruby SDK is the official Ruby SDK for Model Context Protocol servers and clients. Prior to 0.23.0, MCP::Server::Transports::StreamableHTTPTransport in the mcp gem reads and parses an entire JSON-RPC POST body without a size limit, allowing an unauthenticated remote attacker to exhaust process memory. This issue is fixed in version 0.23.0.

EPSS: 0.004 (36.3th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Modelcontextprotocol Ruby-sdk — versions < 0.23.0

Weakness classification (CWE)

CWE-770 — Allocation of Resources Without Limits or Throttling

References

security-advisories@github.com (x_refsource_CONFIRM)
security-advisories@github.com (x_refsource_MISC)
security-advisories@github.com (x_refsource_MISC)

Frequently asked questions

What is CVE-2026-67432?: CVE-2026-67432 is a high-severity vulnerability in Modelcontextprotocol Ruby-Sdk, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 7.5/10. Published 2026-07-29.
How severe is CVE-2026-67432?: High severity. CVSS v3 base score is 7.5 out of 10.