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CVE-2026-67430

MCP Ruby SDK: Unbounded session retention in StreamableHTTPTransport allows memory exhaustion via initialize flood 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 expire sessions by default, so repeated initialize requests retain unbounded ServerSession objects and can exhaust process memory. This issue is fixed in version 0.23.0.

Affected (CNA)

Vendor / productVersions
modelcontextprotocol / ruby-sdkaffected < 0.23.0

CWE

CWE-401, CWE-770

References

ADP enrichment

CISA-ADP

No English description supplied.