{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0.20.0"
              },
              {
                "last_affected": "0.39.0"
              },
              {
                "fixed": "0.39.0"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "DESCRIPTION"
            ]
          },
          "events": [
            {
              "introduced": "e9cb1e643454bc6785aa88c256a7f01803b2506a"
            },
            {
              "fixed": "93cc6b27d7b31ebd7b40fddd1c4c3436bc5a71cf"
            }
          ],
          "repo": "https://github.com/1mcp-app/agent",
          "type": "GIT"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "VulnCheck",
    "cwe_ids": [
      "CWE-863"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/108xxx/CVE-2026-108586.json"
  },
  "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 \u003cgranted-tag\u003e to list and invoke tools on backend MCP servers outside their granted scopes.",
  "id": "CVE-2026-108586",
  "modified": "2026-10-15T02:30:38.889718472Z",
  "published": "2026-10-10T16:14:10.297Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://www.npmjs.com/package/@1mcp/agent"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/108xxx/CVE-2026-108586.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://hackmd.io/@haind/1mcp-negated-tag-filter-oauth-scope-bypass"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-108586"
    },
    {
      "type": "ADVISORY",
      "url": "https://www.vulncheck.com/advisories/1mcp-agent-0.20.0-through-0.39.0-oauth-tag-scope-bypass-via-negated-tag-filter"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/1mcp-app/agent"
    },
    {
      "type": "ARTICLE",
      "url": "https://github.com/1mcp-app/agent/blob/v0.39.0/src/sdk/legacy/transport/http/middlewares/scopeAuthMiddleware.ts#L163-L183"
    },
    {
      "type": "ARTICLE",
      "url": "https://github.com/1mcp-app/agent/blob/v0.39.0/src/transport/http/routes/inspectHelpers.ts#L79-L102"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "1MCP Agent 0.20.0 through 0.39.0 OAuth Tag-Scope Bypass via Negated Tag Filter"
}