CVE-2026-63118

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 validate the HTTP Host or Origin request headers, which allows a malicious browser page to use DNS rebinding to reach a locally running MCP server and invoke exposed tools. This issue is fixed in version 0.23.0.

CVSS

No CVSS.

References

Link	Resource
https://github.com/modelcontextprotocol/ruby-sdk/commit/ba543083a7594e7892b29464b89091816446ff7a
https://github.com/modelcontextprotocol/ruby-sdk/releases/tag/v0.23.0
https://github.com/modelcontextprotocol/ruby-sdk/security/advisories/GHSA-rjr6-rcgv-9m7m
https://github.com/modelcontextprotocol/ruby-sdk/security/advisories/GHSA-rjr6-rcgv-9m7m

Configurations

No configuration.

History

No history.

Information

Published : 2026-07-29 20:17

Updated : 2026-07-30 19:30

NVD link : CVE-2026-63118

Mitre link : CVE-2026-63118

CVE.ORG link : CVE-2026-63118

JSON object : View

Products Affected

No product.

CWE

CWE-346

Origin Validation Error

CWE-350

Reliance on Reverse DNS Resolution for a Security-Critical Action

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