8.3
High
CVE-2026-67431 MCP Ruby SDK is the official Ruby SDK for Model Context Protocol servers and clients
Description
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 does not bind a session ID to a session owner, allowing an attacker with a stolen session ID to send tools/call requests that execute in the victim's session. This issue is fixed in version 0.23.0.
Affected products and versions
| Product | Affected versions | Fixed in |
|---|---|---|
| ruby-sdk 0.23 | earliest → < 0.23.0 | 0.23.0 |
References
- github.com github.com
- github.com github.com
- github.com github.com
Timeline
- Published
- Last modified
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CVE-2026-67430
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