CVE Explorer
CVE-2026-67431
MCP Ruby SDK is the official Ruby SDK for Model Context Protocol servers and clients. Prior to 0.23.0, MCP::Server::Transports::StreamableHTTPTransport in the mcp gem does not bind a session ID to a session owner, allowing an attacker with a stolen session ID to send tools/call requests that execute in the victim's session. This issue is fixed in version 0.23.0.
Known exploited
Not asserted
Disputed
No
Stale source
No
Conflicts
0
Affected products and versions
1 source assertion{"product":"ruby-sdk","vendor":"modelcontextprotocol","versions":[{"status":"affected","version":"< 0.23.0"}]}
- cve_program_cvelist_v5affectedurn:baitaphish:normalized-source-record:v2:4b62f58d69d32f1358c8398c57f59ccd95b51a42c29986181e0192635c600637 · sha256:8cde5dcf4c54eeac… · /containers/cna/affected/0
Provider-owned CVSS observations
1 source assertion{"metric":{"attackComplexity":"LOW","attackRequirements":"PRESENT","attackVector":"NETWORK","baseScore":8.3,"baseSeverity":"HIGH","privilegesRequired":"NONE","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","vectorString":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N","version":"4.0","vulnAvailabilityImpact":"LOW","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"HIGH"},"metric_type":"cvssV4_0"}
- cve_program_cvelist_v5cvssurn:baitaphish:normalized-source-record:v2:4b62f58d69d32f1358c8398c57f59ccd95b51a42c29986181e0192635c600637 · sha256:8cde5dcf4c54eeac… · /containers/cna/metrics/0/cvssV4_0
CWE assertions
1 source assertion{"cweId":"CWE-284","description":"CWE-284: Improper Access Control","lang":"en","type":"CWE"}
- cve_program_cvelist_v5cweurn:baitaphish:normalized-source-record:v2:4b62f58d69d32f1358c8398c57f59ccd95b51a42c29986181e0192635c600637 · sha256:8cde5dcf4c54eeac… · /containers/cna/problemTypes/0/descriptions/0
Source references
4 source assertions{"name":"https://github.com/modelcontextprotocol/ruby-sdk/commit/35466605319a34e4c7808712ae9bb1ca1afb2356","tags":["x_refsource_MISC"],"url":"https://github.com/modelcontextprotocol/ruby-sdk/commit/35466605319a34e4c7808712ae9bb1ca1afb2356"}
- cve_program_cvelist_v5referenceurn:baitaphish:normalized-source-record:v2:4b62f58d69d32f1358c8398c57f59ccd95b51a42c29986181e0192635c600637 · sha256:8cde5dcf4c54eeac… · /containers/cna/references/1
{"name":"https://github.com/modelcontextprotocol/ruby-sdk/releases/tag/v0.23.0","tags":["x_refsource_MISC"],"url":"https://github.com/modelcontextprotocol/ruby-sdk/releases/tag/v0.23.0"}
- cve_program_cvelist_v5referenceurn:baitaphish:normalized-source-record:v2:4b62f58d69d32f1358c8398c57f59ccd95b51a42c29986181e0192635c600637 · sha256:8cde5dcf4c54eeac… · /containers/cna/references/2
{"name":"https://github.com/modelcontextprotocol/ruby-sdk/security/advisories/GHSA-5p9g-j988-pcwv","tags":["x_refsource_CONFIRM"],"url":"https://github.com/modelcontextprotocol/ruby-sdk/security/advisories/GHSA-5p9g-j988-pcwv"}
- cve_program_cvelist_v5referenceurn:baitaphish:normalized-source-record:v2:4b62f58d69d32f1358c8398c57f59ccd95b51a42c29986181e0192635c600637 · sha256:8cde5dcf4c54eeac… · /containers/cna/references/0
{"tags":["exploit"],"url":"https://github.com/modelcontextprotocol/ruby-sdk/security/advisories/GHSA-5p9g-j988-pcwv"}
- cve_program_cvelist_v5referenceurn:baitaphish:normalized-source-record:v2:4b62f58d69d32f1358c8398c57f59ccd95b51a42c29986181e0192635c600637 · sha256:8cde5dcf4c54eeac… · /containers/adp/0/references/0
Attribution and limitations
- CVE Program CVEList V5: Reproduce the MITRE copyright designation and CVE license in copies. Source →
Provider severity values are preserved separately. Baitaphish does not convert them into a risk rating, infer affected products, or treat EPSS as observed exploitation.