CVE-2026-33946: CWE-384: Session Fixation in modelcontextprotocol ruby-sdk
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.
AI Analysis
Technical Summary
The Model Context Protocol Ruby SDK versions before 0.9.2 contain a session fixation vulnerability (CWE-384) in the streamable_http_transport.rb implementation. An attacker who acquires a valid session ID can hijack the victim's SSE stream, gaining unauthorized access to real-time data transmitted over the session. This vulnerability was addressed and fixed in version 0.9.2 of the SDK.
Potential Impact
Successful exploitation allows an unauthenticated attacker to hijack a valid session and intercept all real-time data sent over the Server-Sent Events stream. This compromises confidentiality of the data transmitted via the affected SDK versions prior to 0.9.2.
Mitigation Recommendations
Upgrade to version 0.9.2 or later of the Model Context Protocol Ruby SDK, where the session fixation vulnerability has been patched. No other mitigation steps are indicated by the vendor advisory.
CVE-2026-33946: CWE-384: Session Fixation in modelcontextprotocol ruby-sdk
Description
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.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The Model Context Protocol Ruby SDK versions before 0.9.2 contain a session fixation vulnerability (CWE-384) in the streamable_http_transport.rb implementation. An attacker who acquires a valid session ID can hijack the victim's SSE stream, gaining unauthorized access to real-time data transmitted over the session. This vulnerability was addressed and fixed in version 0.9.2 of the SDK.
Potential Impact
Successful exploitation allows an unauthenticated attacker to hijack a valid session and intercept all real-time data sent over the Server-Sent Events stream. This compromises confidentiality of the data transmitted via the affected SDK versions prior to 0.9.2.
Mitigation Recommendations
Upgrade to version 0.9.2 or later of the Model Context Protocol Ruby SDK, where the session fixation vulnerability has been patched. No other mitigation steps are indicated by the vendor advisory.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-03-24T19:50:52.105Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 69c6f6ca3c064ed76ff81bb3
Added to database: 3/27/2026, 9:29:46 PM
Last enriched: 4/4/2026, 10:59:57 AM
Last updated: 5/11/2026, 5:39:24 AM
Views: 118
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