CVE-2026-67431: CWE-284: Improper Access Control in modelcontextprotocol ruby-sdk
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.
CVE-2026-67431: CWE-284: Improper Access Control in modelcontextprotocol ruby-sdk
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.
CVSS v4.0
Score 8.3high
Weaknesses
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-07-29T15:07:24.991Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a6a53159c2644c7f8f0f10c
Added to database: 07/29/2026, 19:23:01 UTC
Last updated: 07/29/2026, 19:23:01 UTC
Views: 1
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