{
 "public_id": "AIR-2026-0243",
 "incident_id": "2026-09-casdoor-mcp-authz-bypass",
 "date_disclosed": "2026-09-15",
 "date_occurred": null,
 "title": "CVE-2026-91998: Casdoor /api/mcp authorization bypass enables cross-organization user administration",
 "class": "responsible_disclosure",
 "attack_surface": "mcp_server",
 "initial_vector": "application_credential_authz_bypass",
 "agent_capability_abused": [
  "mcp_user_admin_tools"
 ],
 "target_product": "Casdoor",
 "target_vendor": "Casdoor (Casbin)",
 "autonomy_level": "assistant",
 "impact_realized": false,
 "impact_type": [
  "authorization_bypass",
  "cross_tenant_access",
  "account_takeover",
  "credential_disclosure"
 ],
 "blast_radius": "Casdoor <= 4.4.0; any application's clientId/clientSecret grants admin over every organization",
 "cve": [
  "CVE-2026-91998"
 ],
 "taxonomy": {
  "owasp_asi": [
   "ASI03"
  ],
  "mitre_atlas": [],
  "labels": [
   "authorization_bypass",
   "cross_tenant",
   "mcp_endpoint",
   "identity_provider"
  ]
 },
 "defense_present": "Casbin policy + per-organization scoping",
 "defense_bypassed": true,
 "fix_shipped": null,
 "primary_sources": [
  "https://cveawg.mitre.org/api/cve/CVE-2026-91998",
  "https://www.vulncheck.com/advisories/casdoor-through-4.4.0-cross-organization-user-administration-via-api-mcp",
  "https://github.com/geo-chen/oss/blob/main/casdoor.md"
 ],
 "verified_quote": "Casdoor through 4.4.0 contains an authorization bypass vulnerability in the /api/mcp endpoint that allows attackers with any application's clientId and clientSecret to gain unrestricted access to user administration across all organizations.",
 "confidence": "high",
 "notes": "CVSS 9.9 (v3.1) / 9.4 (v4.0). Assigned by VulnCheck; reported by George Chen (geo-chen). authz.go returns an unconditional allow for any subject owned by 'app', skipping Casbin and org scoping. PoC 'confirmed against the built binary' (attacker app credentials read, created an admin and deleted a user in a different organization) - lab confirmation, no real third-party victim, so impact_realized false. No fixed version stated in the advisory at disclosure.",
 "risk_category": "security_fraud",
 "risk_secondary": [],
 "risk_subcategory": "Credential & Secret Theft",
 "risk_sub_secondary": [
  "Unauthorized Access & Account Takeover",
  "Over-permissioned execution & lateral movement"
 ],
 "ai_entity": "generative",
 "agency": "ai_as_target",
 "agency_debatable": false,
 "agency_reason": "MCP endpoint authorization bypass; no model decision",
 "vector_family": "other",
 "vector_detail": "application_credential_authz_bypass",
 "guardrail_kind": [
  "unknown"
 ],
 "guardrail_outcome": "silent",
 "xrefs": {
  "aiid": [],
  "atlas": [],
  "cve": [
   "CVE-2026-91998"
  ],
  "ghsa": []
 },
 "primary_asi": "ASI03",
 "agent_framework": "mcp_server",
 "model_provider": "unknown",
 "model_name": "",
 "detection_mechanism": "unknown",
 "tool_access": "unknown",
 "financial_loss_band": "unknown",
 "eai_category": "credential_theft",
 "eai_domain": "access_control_and_permissions",
 "eai_secondary": [
  "privilege_escalation"
 ],
 "eai_reason": "subcategory: Credential & Secret Theft",
 "asi_curated": [],
 "asi_scope": "in_scope",
 "asi_provenance": "rule",
 "asi_reason": "ASI03 (eai_category=credential_theft)",
 "submitted_by": "EAI Internal"
}