{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-108586","assignerOrgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","state":"PUBLISHED","assignerShortName":"VulnCheck","dateReserved":"2026-10-10T16:07:40.380Z","datePublished":"2026-10-10T16:14:10.297Z","dateUpdated":"2026-10-10T16:14:10.297Z"},"containers":{"cna":{"providerMetadata":{"orgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","shortName":"VulnCheck","dateUpdated":"2026-10-10T16:14:10.297Z"},"datePublic":"2026-10-09T00:00:00.000Z","title":"1MCP Agent 0.20.0 through 0.39.0 OAuth Tag-Scope Bypass via Negated Tag Filter","descriptions":[{"lang":"en","value":"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."}],"problemTypes":[{"descriptions":[{"lang":"en","description":"Incorrect Authorization","cweId":"CWE-863","type":"CWE"}]}],"affected":[{"vendor":"1mcp-app","product":"@1mcp/agent","defaultStatus":"unaffected","versions":[{"version":"0.20.0","lessThanOrEqual":"0.39.0","status":"affected","versionType":"semver"}],"packageURL":"pkg:npm/%401mcp/agent","collectionURL":"https://www.npmjs.com/package/@1mcp/agent","repo":"https://github.com/1mcp-app/agent"}],"metrics":[{"format":"CVSS","cvssV4_0":{"version":"4.0","vectorString":"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","attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"LOW","userInteraction":"NONE","vulnConfidentialityImpact":"LOW","vulnIntegrityImpact":"LOW","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":5.3,"baseSeverity":"MEDIUM"}},{"format":"CVSS","cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"LOW","integrityImpact":"LOW","availabilityImpact":"NONE","baseScore":5.4,"baseSeverity":"MEDIUM"}}],"references":[{"url":"https://hackmd.io/@haind/1mcp-negated-tag-filter-oauth-scope-bypass","tags":["third-party-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"]},{"url":"https://github.com/1mcp-app/agent/blob/v0.39.0/src/transport/http/routes/inspectHelpers.ts#L79-L102","tags":["technical-description"]},{"url":"https://github.com/1mcp-app/agent","tags":["product"]},{"name":"VulnCheck Advisory: 1MCP Agent 0.20.0 through 0.39.0 OAuth Tag-Scope Bypass via Negated Tag Filter","tags":["third-party-advisory"],"url":"https://www.vulncheck.com/advisories/1mcp-agent-0.20.0-through-0.39.0-oauth-tag-scope-bypass-via-negated-tag-filter"}],"credits":[{"lang":"en","value":"HaiND from the Post and Telecommunication Institute of Technology","type":"finder"}],"x_generator":{"engine":"vulncheck-endgame"}}}}