{"cve":{"cve_id":"CVE-2026-9739","is_kev":false,"kev_date_added":null,"kev_vendor_project":null,"kev_product":null,"kev_vulnerability_name":null,"kev_short_description":null,"kev_required_action":null,"kev_due_date":null,"kev_known_ransomware":null,"kev_notes":null,"kev_cwes":null,"epss_score":0.00279,"epss_percentile":0.19498,"epss_as_of":"2026-06-23","description":"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.","published_at":"2026-05-27T21:38:55.833000Z","last_modified_at":null,"cvss_v3_score":null,"cvss_v3_vector":null,"cvss_v3_severity":null,"cvss_v4_score":9.4,"cvss_v4_vector":"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","cvss_v4_severity":"CRITICAL","ssvc_decision":null,"ssvc_exploitation":null,"ssvc_automatable":null,"ssvc_technical_impact":null,"cwes":["CWE-942"],"nvd_references":["https://github.com/googleapis/mcp-toolbox/issues/3053","https://github.com/googleapis/mcp-toolbox/pull/3054"],"vuln_status":null,"trending_score":null,"is_trending":false,"has_trended":false,"trended_number_one":false,"trending_peak_score":null,"trending_peak_rank":null,"started_trending_at":null,"trended_number_one_at":null,"summary_generated":null,"summary_generated_at":null,"summary_model":null,"created_at":"2026-06-24T00:09:39.878444Z","updated_at":"2026-06-28T23:31:14.033653Z"},"effective_severity":"CRITICAL","badges":[],"impact_analysis":[],"cvss_v3_decoded":{"version":null,"metrics":[]},"cvss_v4_decoded":{"version":"4.0","metrics":[{"metric":"AV","name":"Attack Vector","value":"N","value_label":"Network"},{"metric":"AC","name":"Attack Complexity","value":"L","value_label":"Low"},{"metric":"AT","name":"Attack Requirements","value":"N","value_label":"None"},{"metric":"PR","name":"Privileges Required","value":"N","value_label":"None"},{"metric":"UI","name":"User Interaction","value":"A","value_label":"Active"},{"metric":"VC","name":"Confidentiality (Vulnerable System)","value":"H","value_label":"High"},{"metric":"VI","name":"Integrity (Vulnerable System)","value":"H","value_label":"High"},{"metric":"VA","name":"Availability (Vulnerable System)","value":"H","value_label":"High"},{"metric":"SC","name":"Confidentiality (Subsequent System)","value":"H","value_label":"High"},{"metric":"SI","name":"Integrity (Subsequent System)","value":"H","value_label":"High"},{"metric":"SA","name":"Availability (Subsequent System)","value":"H","value_label":"High"}]},"affected":[{"vendor_slug":"google","vendor_name":"Google","product_slug":"mcp-toolbox-for-databases","product_name":"MCP Toolbox for Databases","version_start":"0","version_start_inclusive":true,"version_end":"PR 3054 (Fix CORS bypass)","version_end_inclusive":false,"cpe23_uri":"cve5:google:mcp-toolbox-for-databases:0:PR 3054 (Fix CORS bypass)"}],"exploit_refs":[],"news":[],"references":[{"url":"https://github.com/googleapis/mcp-toolbox/issues/3053","source_type":"MISC","tags":[]},{"url":"https://github.com/googleapis/mcp-toolbox/pull/3054","source_type":"PATCH","tags":["patch"]}],"timeline":[{"type":"published","at":"2026-05-27T21:38:55.833000Z","label":"CVE published","source":null},{"type":"cvss_changed","at":"2026-06-28T17:56:27.543306Z","label":"CVSS score revised","source":"cvelistv5"},{"type":"cvss_changed","at":"2026-06-28T17:56:27.543306Z","label":"CVSS score revised","source":"cvelistv5"},{"type":"cvss_changed","at":"2026-06-28T17:56:27.543306Z","label":"CVSS score revised","source":"cvelistv5"}]}