{"id":"EUVD-2026-37879","revision":"2fc76c1c11424a268991ffa11ae23c11","records":[{"revision":"2fc76c1c11424a268991ffa11ae23c11","observedAt":"2026-11-05T04:05:11.833+00:00","statement":{"source":"euvd","id":"EUVD-2026-37879","aliases":["CVE-2026-11717","GHSA-8fcc-w5hv-4gxv"],"title":"An authentication bypass vulnerability exists in the generic opaque token validation path (validateOpaqueToken) of googleapis/mcp-toolbox.","description":"An authentication bypass vulnerability exists in the generic opaque token validation path (validateOpaqueToken) of googleapis/mcp-toolbox.\n\nWhen verifying an unparsed opaque token via an OAuth 2.0 introspection endpoint (RFC 7662), the toolbox decodes the response into an introspectResp struct where the Active field is declared as a pointer to a boolean (*bool). The code only explicitly rejects a token if the response contains a populated active field set to false (if introspectResp.Active != nil && !*introspectResp.Active). If an introspection endpoint responds with a payload that completely omits the mandatory active key, the internal variable remains nil, causing the conditional check to short-circuit. As a result, Toolbox accepts authorization tokens missing the \"active\" field, granting access to protected tools and underlying data sources.","state":0,"publishedAt":null,"modifiedAt":null,"affected":[],"metrics":[{"system":"EUVD CVSS 4.0","vector":"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","score":9.3,"severity":null}],"references":["https://github.com/googleapis/mcp-toolbox/pull/3341"],"sourceUrl":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-37879","license":"ENISA EUVD · source terms and attribution apply","enrichment":{"sourceStatus":null,"weaknesses":[],"productCriteria":[],"sourceDates":{"datePublished":"Jun 18, 2026, 11:50:23 AM","dateUpdated":"Jun 18, 2026, 12:23:15 PM"},"relatedAdvisories":[],"note":"EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON."},"key":"euvd:EUVD-2026-37879","identifiers":["EUVD-2026-37879","CVE-2026-11717","GHSA-8fcc-w5hv-4gxv"]},"retained":false,"historicalAffected":[]}],"coverage":[]}