CVE-2026-33946 — MCP Ruby SDK: Insufficient Session Binding Allows SSE Stream Hijacking via Session ID Replay
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…
Published: 2026-03-27 · CVSS: 8.2 · CVSS 4.0
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.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7