{"id":"CVE-2026-108586","aliases":["EUVD-2026-96373","GHSA-w2j7-xxh9-9q67"],"status":"published","title":"1MCP Agent 0.20.0 through 0.39.0 OAuth Tag-Scope Bypass via Negated Tag Filter","description":"1MCP Agent (@1mcp/agent) 0.20.0 through 0.39.0 contains an incorrect authorization vulnerability that allows authenticated clients to bypass OAuth tag-scope enforcement using negated advanced tag-filter expressions. Attackers holding a single-tag token can send a filter like not \u003cgranted-tag\u003e to list and invoke tools on backend MCP servers outside their granted scopes.","severity":{"version":"4.0","score":5.3,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.0019,"percentile":0.08778,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-863"],"published":"2026-10-10T16:14:10Z","modified":"2026-10-28T02:30:34Z","products":[{"vendor":"1mcp-app","product":"@1mcp/agent"}],"references":[{"url":"https://hackmd.io/@haind/1mcp-negated-tag-filter-oauth-scope-bypass","tags":["third-party-advisory","advisory"]},{"url":"https://github.com/1mcp-app/agent/blob/v0.39.0/src/sdk/legacy/transport/http/middlewares/scopeAuthMiddleware.ts#L163-L183","tags":["technical-description","article"]},{"url":"https://github.com/1mcp-app/agent/blob/v0.39.0/src/transport/http/routes/inspectHelpers.ts#L79-L102","tags":["technical-description","article"]},{"url":"https://github.com/1mcp-app/agent","tags":["product","package"]},{"url":"https://www.vulncheck.com/advisories/1mcp-agent-0.20.0-through-0.39.0-oauth-tag-scope-bypass-via-negated-tag-filter","tags":["third-party-advisory","advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-108586","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-w2j7-xxh9-9q67"},{"url":"https://www.npmjs.com/package/@1mcp/agent","tags":["web"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/108xxx/CVE-2026-108586.json","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2026-108586","title":"1MCP Agent 0.20.0 through 0.39.0 OAuth Tag-Scope Bypass via Negated Tag Filter","description":"1MCP Agent (@1mcp/agent) 0.20.0 through 0.39.0 contains an incorrect authorization vulnerability that allows authenticated clients to bypass OAuth tag-scope enforcement using negated advanced tag-filter expressions. Attackers holding a single-tag token can send a filter like not \u003cgranted-tag\u003e to list and invoke tools on backend MCP servers outside their granted scopes.","status":"published","published":"2026-10-10T16:14:10.297Z","modified":"2026-10-13T18:27:18.799Z","cvss":[{"version":"4.0","score":5.3,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N","level":"medium","assessor":"cna"},{"version":"3.1","score":5.4,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N","level":"medium","assessor":"cna"}],"cwes":["CWE-863"],"updated_at":"2026-11-02T14:20:10.510075Z"}],"euvd":[{"id":"EUVD-2026-96373","description":"1MCP Agent (@1mcp/agent) 0.20.0 through 0.39.0 contains an incorrect authorization vulnerability that allows authenticated clients to bypass OAuth tag-scope enforcement using negated advanced tag-filter expressions. Attackers holding a single-tag token can send a filter like not \u003cgranted-tag\u003e to list and invoke tools on backend MCP servers outside their granted scopes.","status":"published","published":"2026-10-10T16:14:10Z","modified":"2026-10-13T18:27:18Z","cvss":[{"version":"4.0","score":5.3,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N","level":"medium"}],"updated_at":"2026-11-02T17:27:19.128463Z"}],"ghsa":[{"id":"GHSA-w2j7-xxh9-9q67","title":"1MCP Agent (@1mcp/agent) 0.20.0 through 0.39.0 contains an incorrect authorization vulnerability...","description":"1MCP Agent (@1mcp/agent) 0.20.0 through 0.39.0 contains an incorrect authorization vulnerability that allows authenticated clients to bypass OAuth tag-scope enforcement using negated advanced tag-filter expressions. Attackers holding a single-tag token can send a filter like not \u003cgranted-tag\u003e to list and invoke tools on backend MCP servers outside their granted scopes.","status":"published","published":"2026-10-10T18:31:20Z","modified":"2026-10-10T18:31:26Z","cvss":[{"version":"4.0","score":5.3,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"medium"},{"version":"3.1","score":5.4,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N","level":"medium"}],"cwes":["CWE-863"],"updated_at":"2026-11-02T15:13:02.546582Z"}],"nvd":[{"id":"CVE-2026-108586","description":"1MCP Agent (@1mcp/agent) 0.20.0 through 0.39.0 contains an incorrect authorization vulnerability that allows authenticated clients to bypass OAuth tag-scope enforcement using negated advanced tag-filter expressions. Attackers holding a single-tag token can send a filter like not \u003cgranted-tag\u003e to list and invoke tools on backend MCP servers outside their granted scopes.","status":"published","published":"2026-10-10T17:17:00.593Z","modified":"2026-10-16T19:21:14.417Z","cvss":[{"version":"4.0","score":5.3,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"medium","assessor":"secondary"},{"version":"3.1","score":5.4,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N","level":"medium","assessor":"secondary"}],"cwes":["CWE-863"],"updated_at":"2026-11-02T14:12:55.874869Z"}],"osv":[{"id":"CVE-2026-108586","title":"1MCP Agent 0.20.0 through 0.39.0 OAuth Tag-Scope Bypass via Negated Tag Filter","description":"1MCP Agent (@1mcp/agent) 0.20.0 through 0.39.0 contains an incorrect authorization vulnerability that allows authenticated clients to bypass OAuth tag-scope enforcement using negated advanced tag-filter expressions. Attackers holding a single-tag token can send a filter like not \u003cgranted-tag\u003e to list and invoke tools on backend MCP servers outside their granted scopes.","status":"published","published":"2026-10-10T16:14:10.297Z","modified":"2026-10-28T02:30:34.234701238Z","cvss":[{"version":"4.0","score":5.3,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N","level":"medium"}],"cwes":["CWE-863"],"updated_at":"2026-11-02T15:44:54.933106Z"}]}}