{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-9739","assignerOrgId":"14ed7db2-1595-443d-9d34-6215bf890778","state":"PUBLISHED","assignerShortName":"Google","dateReserved":"2026-05-27T17:31:41.604Z","datePublished":"2026-05-27T21:38:55.833Z","dateUpdated":"2026-05-28T13:20:43.816Z"},"containers":{"cna":{"providerMetadata":{"orgId":"14ed7db2-1595-443d-9d34-6215bf890778","shortName":"Google","dateUpdated":"2026-05-27T21:38:55.833Z"},"problemTypes":[{"descriptions":[{"lang":"en","cweId":"CWE-942","description":"CWE-942: Permissive Cross-domain Policy with Untrusted Domains","type":"CWE"}]}],"impacts":[{"capecId":"CAPEC-275","descriptions":[{"lang":"en","value":"CAPEC-275: DNS Rebinding"}]}],"affected":[{"vendor":"Google","product":"MCP Toolbox for Databases","versions":[{"status":"affected","version":"0","lessThan":"PR 3054 (Fix CORS bypass)","versionType":"custom"}],"defaultStatus":"unaffected"}],"descriptions":[{"lang":"en","value":"Vulnerable to DNS rebinding attacks when using SSE (http://b/499408790). During the beta phase, we implemented `allowed-origins` and `allowed-hosts` flags to align with MCP security guidelines. However, the hardcoded `Access-Control-Allow-Origin: *` header in the SSE initialization handler was inadvertently retained. This vulnerability specifically impacts users connecting via Toolbox using SSE under specification v2024-11-05.","supportingMedia":[{"type":"text/html","base64":false,"value":"Vulnerable to DNS rebinding attacks when using SSE (http://b/499408790). During the beta phase, we implemented `allowed-origins` and `allowed-hosts` flags to align with MCP security guidelines. However, the hardcoded `Access-Control-Allow-Origin: *` header in the SSE initialization handler was inadvertently retained. This vulnerability specifically impacts users connecting via Toolbox using SSE under specification v2024-11-05."}]}],"references":[{"url":"https://github.com/googleapis/mcp-toolbox/issues/3053"},{"url":"https://github.com/googleapis/mcp-toolbox/pull/3054"}],"metrics":[{"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}],"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"ACTIVE","vulnConfidentialityImpact":"HIGH","subConfidentialityImpact":"HIGH","vulnIntegrityImpact":"HIGH","subIntegrityImpact":"HIGH","vulnAvailabilityImpact":"HIGH","subAvailabilityImpact":"HIGH","exploitMaturity":"NOT_DEFINED","Safety":"NOT_DEFINED","Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","valueDensity":"NOT_DEFINED","vulnerabilityResponseEffort":"NOT_DEFINED","providerUrgency":"NOT_DEFINED","version":"4.0","baseSeverity":"CRITICAL","baseScore":9.4,"vectorString":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H"}}],"source":{"discovery":"UNKNOWN"},"x_generator":{"engine":"Vulnogram 1.0.2"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-05-28T13:19:37.204820Z","id":"CVE-2026-9739","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-05-28T13:20:43.816Z"}}]}}