{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-33946","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","state":"PUBLISHED","assignerShortName":"GitHub_M","dateReserved":"2026-03-24T19:50:52.105Z","datePublished":"2026-03-27T21:20:07.900Z","dateUpdated":"2026-03-30T18:42:43.387Z"},"containers":{"cna":{"title":"MCP Ruby SDK: Insufficient Session Binding Allows SSE Stream Hijacking via Session ID Replay","problemTypes":[{"descriptions":[{"cweId":"CWE-384","lang":"en","description":"CWE-384: Session Fixation","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-639","lang":"en","description":"CWE-639: Authorization Bypass Through User-Controlled Key","type":"CWE"}]}],"metrics":[{"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"PRESENT","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"HIGH","vulnIntegrityImpact":"NONE","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":8.2,"baseSeverity":"HIGH","vectorString":"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","version":"4.0"}}],"references":[{"name":"https://github.com/modelcontextprotocol/ruby-sdk/security/advisories/GHSA-qvqr-5cv7-wh35","tags":["x_refsource_CONFIRM"],"url":"https://github.com/modelcontextprotocol/ruby-sdk/security/advisories/GHSA-qvqr-5cv7-wh35"},{"name":"https://github.com/modelcontextprotocol/ruby-sdk/commit/db40143402d65b4fb6923cec42d2d72cb89b3874","tags":["x_refsource_MISC"],"url":"https://github.com/modelcontextprotocol/ruby-sdk/commit/db40143402d65b4fb6923cec42d2d72cb89b3874"},{"name":"https://hackerone.com/reports/3556146","tags":["x_refsource_MISC"],"url":"https://hackerone.com/reports/3556146"},{"name":"https://github.com/modelcontextprotocol/csharp-sdk/blob/main/src/ModelContextProtocol.AspNetCore/SseHandler.cs#L93-L97","tags":["x_refsource_MISC"],"url":"https://github.com/modelcontextprotocol/csharp-sdk/blob/main/src/ModelContextProtocol.AspNetCore/SseHandler.cs#L93-L97"},{"name":"https://github.com/modelcontextprotocol/go-sdk/blob/main/mcp/streamable.go#L281C1-L288C2","tags":["x_refsource_MISC"],"url":"https://github.com/modelcontextprotocol/go-sdk/blob/main/mcp/streamable.go#L281C1-L288C2"},{"name":"https://github.com/modelcontextprotocol/python-sdk/blob/main/src/mcp/server/streamable_http.py#L680-L685","tags":["x_refsource_MISC"],"url":"https://github.com/modelcontextprotocol/python-sdk/blob/main/src/mcp/server/streamable_http.py#L680-L685"},{"name":"https://github.com/modelcontextprotocol/ruby-sdk/blob/main/examples/streamable_http_server.rb","tags":["x_refsource_MISC"],"url":"https://github.com/modelcontextprotocol/ruby-sdk/blob/main/examples/streamable_http_server.rb"},{"name":"https://github.com/modelcontextprotocol/ruby-sdk/releases/tag/v0.9.2","tags":["x_refsource_MISC"],"url":"https://github.com/modelcontextprotocol/ruby-sdk/releases/tag/v0.9.2"}],"affected":[{"vendor":"modelcontextprotocol","product":"ruby-sdk","versions":[{"version":"< 0.9.2","status":"affected"}]}],"providerMetadata":{"orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","shortName":"GitHub_M","dateUpdated":"2026-03-27T21:20:07.900Z"},"descriptions":[{"lang":"en","value":"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":{"advisory":"GHSA-qvqr-5cv7-wh35","discovery":"UNKNOWN"}},"adp":[{"references":[{"url":"https://github.com/modelcontextprotocol/ruby-sdk/security/advisories/GHSA-qvqr-5cv7-wh35","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-03-30T18:42:40.211983Z","id":"CVE-2026-33946","options":[{"Exploitation":"poc"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-03-30T18:42:43.387Z"}}]}}