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CVE-2026-33946

MCP Ruby SDK: Insufficient Session Binding Allows SSE Stream Hijacking via Session ID Replay PUBLISHED

Description (CNA)

MCP Ruby SDK is the official Ruby SDK for Model Context Protocol servers and clients. Prior to version 0.9.2, the Ruby SDK's streamable_http_transport.rb implementation contains a session hijacking vulnerability. An attacker who obtains a valid session ID can completely hijack the victim's Server-Sent Events (SSE) stream and intercept all real-time data. Version 0.9.2 contains a patch.

Affected (CNA)

Vendor / productVersions
modelcontextprotocol / ruby-sdkaffected < 0.9.2

CWE

CWE-384, CWE-639

References

ADP enrichment

CISA-ADP

No English description supplied.