CVE-2026-33946
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.
Scoring
- Severity
- HIGH
- CVSS base score
- 8.2
- CVSS vector
- CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
- EPSS probability
- 0.46%
- CWE
- CWE-384, CWE-639
- Published
- 2026-03-27
- Last modified
- 2026-03-30
Affected products
- modelcontextprotocol ruby-sdk
Weakness type
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