← CVE Intelligence

CVE-2026-63118

MCP Ruby SDK: Streamable HTTP transport lacks DNS-rebinding (Host/Origin) protection PUBLISHED

Description (CNA)

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.

Affected (CNA)

Vendor / productVersions
modelcontextprotocol / ruby-sdkaffected < 0.23.0

CWE

CWE-346, CWE-350

References

ADP enrichment

CISA-ADP

No English description supplied.