CVE-2026-67432 (High) detected in mcp-0.9.0.gem
Nobody has claimed this yet.
- Dominant language
- Ruby
- Stars
- 259
- Forks
- 35
- PR merge metrics
- No merged PRs in 30d
Description
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-performance-1.26.1.gem
- rubocop-1.85.1.gem
- ❌ mcp-0.9.0.gem (Vulnerable Library)
- rubocop-1.85.1.gem
- rubocop-performance-1.26.1.gem
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
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
Step up your Open Source Security Game with Mend here
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with Gemfile.lock and the vendor/cache/mcp-0.9.0.gem path, tracing the rubocop-performance and rubocop dependency chain described in the issue. Update the resolved MCP dependency to version 0.23.0 or later, then verify that the lockfile and vendored dependency no longer select the vulnerable version.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- ruby
- Domain
- security
- Issue type
- Bug
- Difficulty
- 2/5
- Estimated time
- 1-3 hours
- Activity status
- Quiet
- Clarity
- Clearly specified
- Newbie friendliness
- 72/100