{"id":"CVE-2026-108586","published":"2026-10-10T17:17:00.593","lastModified":"2026-10-16T19:21:14.417","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 <granted-tag> to list and invoke tools on backend MCP servers outside their granted scopes.","cvssScore":5.4,"cvssSeverity":"MEDIUM","cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N","cwes":["CWE-863"],"vendors":[],"products":[],"references":[{"url":"https://github.com/1mcp-app/agent","tags":[]},{"url":"https://github.com/1mcp-app/agent/blob/v0.39.0/src/sdk/legacy/transport/http/middlewares/scopeAuthMiddleware.ts#L163-L183","tags":[]},{"url":"https://github.com/1mcp-app/agent/blob/v0.39.0/src/transport/http/routes/inspectHelpers.ts#L79-L102","tags":[]},{"url":"https://hackmd.io/@haind/1mcp-negated-tag-filter-oauth-scope-bypass","tags":[]},{"url":"https://www.vulncheck.com/advisories/1mcp-agent-0.20.0-through-0.39.0-oauth-tag-scope-bypass-via-negated-tag-filter","tags":[]}],"exploitRefs":[{"url":"https://github.com/1mcp-app/agent","tags":[]},{"url":"https://github.com/1mcp-app/agent/blob/v0.39.0/src/sdk/legacy/transport/http/middlewares/scopeAuthMiddleware.ts#L163-L183","tags":[]},{"url":"https://github.com/1mcp-app/agent/blob/v0.39.0/src/transport/http/routes/inspectHelpers.ts#L79-L102","tags":[]}],"hasPoc":true,"ai":null}