CVE-2026-63119 (Medium) detected in mcp-0.9.0.gem

Nobody has claimed this yet.

## CVE-2026-63119 - Medium 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-performance-1.26.1.gem
- 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::StdioTransport and MCP::Client::Stdio in the mcp gem use IO#gets without a byte limit, allowing a peer that sends data without a newline to exhaust process memory. This issue is fixed in version 0.23.0.

Publish Date: 2026-07-29

URL: CVE-2026-63119

CVSS 3 Score Details (6.2)

Base Score Metrics:
- Exploitability Metrics:
- Attack Vector: Local
- 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-7683-3w9x-ch42

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; inspect how mcp is brought in through the listed RuboCop dependencies. Update the resolved mcp version to the stated fixed release, then run the repository's dependency or security checks and confirm the vulnerable version is no longer present.

Written by the indexing model from the issue text.