{"schema":"threatline.record/2","record":{"id":"CVE-2026-108586","aliases":[],"summary":"1MCP Agent 0.20.0 through 0.39.0 OAuth Tag-Scope Bypass via Negated Tag Filter","details":"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 <granted-tag> to list and invoke tools on backend MCP servers outside their granted scopes.","categories":["Unclassified"],"product":"@1mcp/agent","vendor":"1mcp-app","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-108586","source_modified_at":"2026-10-13T18:27:18.799Z","fetched_at":"2026-10-23T18:48:36.087640Z","product":"@1mcp/agent","vendor":"1mcp-app","versions":[{"version":"0.20.0","lessThanOrEqual":"0.39.0","status":"affected","versionType":"semver"}],"defaultStatus":"unaffected"}],"fixed_versions":[],"cvss":5.3,"severity":"Medium","kev":{"listed":false},"epss":{"probability":0.0019,"percentile":0.0824,"score_date":"2026-10-23"},"published_at":"2026-10-10T16:14:10.297Z","modified_at":"2026-10-13T18:27:18.799Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-108586","fetched_at":"2026-10-23T18:48:36.087640Z","source_modified_at":"2026-10-13T18:27:18.799Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-108586","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["CVE List","EPSS"],"references":[{"source":"CVE List","url":"https://hackmd.io/@haind/1mcp-negated-tag-filter-oauth-scope-bypass","tags":["third-party-advisory"]},{"source":"CVE List","url":"https://github.com/1mcp-app/agent/blob/v0.39.0/src/sdk/legacy/transport/http/middlewares/scopeAuthMiddleware.ts#L163-L183","tags":["technical-description"]},{"source":"CVE List","url":"https://github.com/1mcp-app/agent/blob/v0.39.0/src/transport/http/routes/inspectHelpers.ts#L79-L102","tags":["technical-description"]},{"source":"CVE List","url":"https://github.com/1mcp-app/agent","tags":["product"]},{"source":"CVE List","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"]}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","cvss_source":"CVE List","ssvc":{"exploitation":"none","automatable":"no","technical_impact":"partial","assessed_at":"2026-10-13T18:27:08.982440Z"},"classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":null,"confidence":"unknown","reviewed":false},"change_timestamp":"2026-10-13T18:27:18.799Z","content_hash":"211de68ff96b24d0b82d963bdf04211590cf6d4f516022384e50c15f999b982f"}}