{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-14541", "assignerOrgId": "14ed7db2-1595-443d-9d34-6215bf890778", "state": "PUBLISHED", "assignerShortName": "Google", "dateReserved": "2026-07-03T03:38:02.749Z", "datePublished": "2026-07-31T01:48:39.019Z", "dateUpdated": "2026-07-31T01:48:39.019Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "14ed7db2-1595-443d-9d34-6215bf890778", "shortName": "Google", "dateUpdated": "2026-07-31T01:48:39.019Z"}, "title": "Authentication Bypass and Audience Confusion in MCP Toolbox OAuth Provider", "problemTypes": [{"descriptions": [{"lang": "en", "cweId": "CWE-287", "description": "CWE-287 (Improper Authentication)", "type": "CWE"}]}], "impacts": [{"capecId": "CAPEC-115", "descriptions": [{"lang": "en", "value": "CAPEC-115 Authentication Bypass"}]}], "affected": [{"vendor": "Google", "product": "mcp-toolbox", "versions": [{"status": "affected", "version": "1.4.0", "versionType": "semver"}], "defaultStatus": "unaffected"}], "descriptions": [{"lang": "en", "value": "An authentication bypass and audience confusion vulnerability exists in the Google OAuth provider component of Google mcp-toolbox version 1.4.0. When a Google authService is initialized with mcpEnabled: true but lacks an explicitly defined audience or clientId, the ValidateMCPAuth pipeline for opaque tokens skips audience validation entirely. As a result, the toolbox will accept any valid Google OAuth access token\u2014even those minted for unrelated ecosystem applications\u2014granting unauthorized clients access to protected tools and data backends.", "supportingMedia": [{"type": "text/html", "base64": false, "value": "An authentication bypass and audience confusion vulnerability exists in the Google OAuth provider component of Google mcp-toolbox version 1.4.0. When a Google authService is initialized with mcpEnabled: true but lacks an explicitly defined audience or clientId, the ValidateMCPAuth pipeline for opaque tokens skips audience validation entirely. As a result, the toolbox will accept any valid Google OAuth access token\u2014even those minted for unrelated ecosystem applications\u2014granting unauthorized clients access to protected tools and data backends."}]}], "references": [{"url": "https://github.com/googleapis/mcp-toolbox/pull/3450"}], "metrics": [{"format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}], "cvssV4_0": {"attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "HIGH", "subConfidentialityImpact": "NONE", "vulnIntegrityImpact": "HIGH", "subIntegrityImpact": "NONE", "vulnAvailabilityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "UNREPORTED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "version": "4.0", "baseSeverity": "HIGH", "baseScore": 8, "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:U"}}], "credits": [{"lang": "en", "value": "HE WEI (\u30ae\u30ab\u30af)", "type": "finder"}], "source": {"discovery": "UNKNOWN"}, "x_generator": {"engine": "Vulnogram 1.0.2"}}}}

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