MCP Ruby SDK Vulnerability: DNS-Rebinding Protection Missing
The MCP Ruby SDK's Streamable HTTP transport reportedly lacks DNS-rebinding protection, which may allow cross-origin attacks to enumerate and invoke tools and exfiltrate data. Users of the affected mcp gem version 0.18.0 should assess their exposure.
What happened
An early warning has been issued regarding a potential vulnerability in the MCP Ruby SDK's Streamable HTTP transport. The issue, tracked under GHSA-RJR6-RCGV-9M7M, appears to involve a lack of DNS-rebinding protection, which may enable cross-origin attacks. These attacks could potentially allow an attacker to enumerate and invoke tools, as well as exfiltrate data. The affected component is the mcp gem version 0.18.0. It is under investigation whether a compromise has occurred. For now, the recommended action is to review local MCP server configurations for potential exposure. Once a patched version of the mcp gem becomes available, users are advised to upgrade. Primary sources should be consulted for the most current information.
How 0Day mitigates this
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