Security advisory

{
  "id": "96a264362ced08220340e1fc21c53e7b132a521d1c269b0469db8a9e88e1f722",
  "url": "https://osv.dev/vulnerability/CVE-2026-79537",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2026-79537",
    "summary": "metatool-ai MetaMCP through 2.4.22 contains an insecure direct object reference (IDOR) in the MCP transport session dispatch. The session store (getSession in session-lifetime-manager.ts) is keyed only by the client-supplied mcp-session-id header with no owner, namespace, or endpoint binding, and the per-endpoint authorization middleware validates only the URL endpoint's owner, never the session. An attacker who supplies another tenant's session id \" obtained without authentication from GET /metamcp/health/sessions, which discloses active session IDs and namespace UUIDs \" can list and execute the victim tenant's private MCP tools and exfiltrate their data using the victim's forwarded credentials.",
    "evidence": "osv:CVE-2026-79537",
    "products": [],
    "severity": "critical",
    "structured": {
      "id": "CVE-2026-79537",
      "aliases": [
        "CVE-2026-79537"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/metatool-ai/metamcp",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "last_affected": "32b6e9813acfc13d1013eb2452be1899d6654bb9"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "last_affected": "2.4.22"
                      }
                    ],
                    "source": "DESCRIPTION"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v2.4.22",
            "v2.4.16",
            "v2.4.21",
            "v2.4.20",
            "v2.4.19",
            "v2.4.18",
            "v2.4.15",
            "v2.4.17",
            "v2.4.14",
            "v2.4.13",
            "v2.4.12",
            "v2.4.11",
            "v2.4.10",
            "v2.4.9",
            "v2.4.8",
            "v2.4.6",
            "v2.4.7",
            "v2.4.5",
            "v2.3.8",
            "v2.3.7",
            "v2.3.6",
            "v2.3.5",
            "v2.3.4",
            "v2.3.3",
            "v2.3.2",
            "v2.3.1",
            "v2.3.0",
            "v2.2.5",
            "v2.2.4",
            "v2.2.3",
            "v2.2.2",
            "v2.2.1",
            "v2.2.0",
            "v2.1.1",
            "v2.1.0",
            "v2.0.6",
            "v2.0.5",
            "v2.0.3",
            "v2.0.2",
            "v2.0.1",
            "v2.0.0",
            "v0.6.0",
            "v0.5.3",
            "v0.5.2",
            "v0.5.0",
            "v0.4.5",
            "v0.4.3",
            "v0.4.2",
            "v0.4.0",
            "v0.3.2",
            "v0.0.2",
            "v0.0.1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-79537.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:30.614932211Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/79xxx/CVE-2026-79537.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-79537",
        "https://www.traceforce.ai/security-advisories/cve-2026-79537",
        "https://github.com/metatool-ai/metamcp"
      ],
      "provider_metadata": {
        "cna_assigner": "mitre",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/79xxx/CVE-2026-79537.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-79537",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 497661,
  "published_at": "2026-09-29T00:00:00+00:00"
}