mcp Known Vulnerabilities & Fixes
mcp has 6 known security vulnerabilities in RubyGems (Ruby). Upgrade to version 0.23.0 or later to resolve all known issues. Data sourced from OSV, enriched with EPSS exploit probability and CISA KEV.
Low Immediate Risk
No actively exploited vulnerabilities detected. Monitor and update in your next maintenance window.
Recommended safe version: 0.23.0
Upgrading to 0.23.0 or later resolves all 6 known vulnerabilities in mcp. Run: gem install mcp -v 0.23.0
Is mcp in your project?
Check if you're affected and upgrade to 0.23.0 to stay secure.
Security Summary
- 6 affected version ranges have been identified across these 6 advisories.
- 100% of known issues have a published fixed version.
- Remediation: gem update mcp
Vulnerabilities
6 unique vulnerabilities — sorted by exploitation risk (KEV → EPSS → CVSS). Click a CVE/GHSA ID for full details. First disclosed Mar 27, 2026, most recently Jul 30, 2026 (125 days apart).
| CVE / GHSA | Severity | Affected | Fixed In |
|---|---|---|---|
| CVE-2026-67431 MCP Ruby SDK: Ruby SSE Session Poisoning | HIGH | 0.1.0, 0.10.0, 0.11.0, 0.12.0 (+21 more) | 0.23.0 |
| CVE-2026-67432 MCP Ruby SDK: Unbounded JSON-RPC request body causes uncontrolled memory allocation in StreamableHTTPTransport | HIGH | 0.1.0, 0.10.0, 0.11.0, 0.12.0 (+21 more) | 0.23.0 |
| CVE-2026-33946 MCP Ruby SDK: Insufficient Session Binding Allows SSE Stream Hijacking via Session ID Replay | HIGH | 0.1.0, 0.2.0, 0.3.0, 0.4.0 (+7 more) | 0.9.2 |
| CVE-2026-63118 MCP Ruby SDK: Streamable HTTP transport lacks DNS-rebinding (Host/Origin) protection | MEDIUM | 0.1.0, 0.10.0, 0.11.0, 0.12.0 (+21 more) | 0.23.0 |
| CVE-2026-63119 MCP Ruby SDK: Unbounded line buffer in stdio transports leads to memory exhaustion (DoS) | MEDIUM | 0.1.0, 0.10.0, 0.11.0, 0.12.0 (+21 more) | 0.23.0 |
| CVE-2026-67430 MCP Ruby SDK: Unbounded session retention in StreamableHTTPTransport allows memory exhaustion via initialize flood | MEDIUM | 0.1.0, 0.10.0, 0.11.0, 0.12.0 (+21 more) | 0.23.0 |
About This Data
Vulnerability data for mcp is sourced from the Open Source Vulnerability (OSV) database, aggregating reports from GitHub Advisory Database, NIST NVD, and ecosystem-specific sources.
CVSS (Common Vulnerability Scoring System) scores reflect exploitability and impact. EPSS (Exploit Prediction Scoring System) scores indicate the probability of exploitation within the next 30 days. Vulnerabilities marked with are listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.
Related RubyGems (Ruby) Packages
Other packages in this ecosystem, ranked by shared vulnerabilities where available.
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