CVE-2026-67432 (High) detected in mcp-0.9.0.gem

## CVE-2026-67432 - High Severity Vulnerability
Vulnerable Library - mcp-0.9.0.gem

The official Ruby SDK for Model Context Protocol servers and clients

Library home page: https://rubygems.org/gems/mcp-0.9.0.gem

Path to dependency file: /Gemfile.lock

Path to vulnerable library: /vendor/cache/mcp-0.9.0.gem

Dependency Hierarchy:
- manageiq-style-1.6.0.gem (Root Library)
- rubocop-1.85.1.gem
- :x: **mcp-0.9.0.gem** (Vulnerable Library)

Found in base branch: master

Vulnerability Details

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.

Publish Date: 2026-07-29

URL: CVE-2026-67432

CVSS 3 Score Details (7.5)

Base Score Metrics:
- Exploitability Metrics:
- Attack Vector: Network
- Attack Complexity: Low
- Privileges Required: None
- User Interaction: None
- Scope: Unchanged
- Impact Metrics:
- Confidentiality Impact: None
- Integrity Impact: None
- Availability Impact: High

For more information on CVSS3 Scores, click here.

Suggested Fix

Type: Upgrade version

Origin: https://github.com/advisories/GHSA-h669-8m4g-r2hc

Release Date: 2026-07-29

Fix Resolution: mcp - 0.23.0

***
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Start with Gemfile.lock and the vendored dependency at /vendor/cache/mcp-0.9.0.gem. Check how rubocop brings in mcp, then update the dependency so mcp resolves to 0.23.0 or later. Confirm the lockfile and vendor cache no longer contain the vulnerable 0.9.0 release.

Written by the indexing model from the issue text.