{
 "public_id": "AIR-2026-0241",
 "incident_id": "2026-09-bifrost-mcp-client-unauth-rce",
 "date_disclosed": "2026-09-14",
 "date_occurred": null,
 "title": "CVE-2026-90898: unauthenticated RCE in Bifrost via MCP stdio client registration",
 "class": "responsible_disclosure",
 "attack_surface": "mcp_server",
 "initial_vector": "unauthenticated_network_request",
 "agent_capability_abused": [
  "mcp_client_registration",
  "local_process_spawn"
 ],
 "target_product": "Bifrost (AI gateway)",
 "target_vendor": "Maxim (maximhq)",
 "autonomy_level": "assistant",
 "impact_realized": false,
 "impact_type": [
  "remote_code_execution",
  "server_side_request_forgery"
 ],
 "blast_radius": "Bifrost transports < 2.1.0 with default governance.auth_config.is_enabled=false",
 "cve": [
  "CVE-2026-90898"
 ],
 "taxonomy": {
  "owasp_asi": [
   "ASI05",
   "ASI03"
  ],
  "mitre_atlas": [],
  "labels": [
   "missing_authentication",
   "remote_code_execution",
   "mcp_client_registration",
   "ssrf",
   "ai_gateway"
  ]
 },
 "defense_present": "governance auth (disabled by default)",
 "defense_bypassed": true,
 "fix_shipped": "Bifrost transports/v2.1.0",
 "primary_sources": [
  "https://cveawg.mitre.org/api/cve/CVE-2026-90898",
  "https://github.com/maximhq/bifrost/pull/6757",
  "https://cvebrief.com/archive/2026/09/15/"
 ],
 "verified_quote": "One unauthenticated POST /api/mcp/client is enough to run a program as the Bifrost process user (appuser on the official image).",
 "confidence": "high",
 "notes": "CVSS 9.8. Assigned by JFrog; reported by Yuval Moravchick (JFrog). Registering a stdio MCP client makes Bifrost exec() an arbitrary command; an http/sse client enables SSRF to 169.254.169.254. Fixed by refusing unauthenticated stdio/private-target registration (403). PoC/disclosure; no real victim.",
 "risk_category": "security_fraud",
 "risk_secondary": [],
 "risk_subcategory": "Server-Side Request Forgery via LLM",
 "risk_sub_secondary": [
  "Remote Code Execution & Sandbox Escape"
 ],
 "ai_entity": "generative",
 "agency": "ai_as_target",
 "agency_debatable": false,
 "agency_reason": "MCP client registration RCE; no model decision",
 "vector_family": "conventional_vulnerability",
 "vector_detail": "unauthenticated_network_request",
 "guardrail_kind": [
  "authentication"
 ],
 "guardrail_outcome": "not_enabled",
 "xrefs": {
  "aiid": [],
  "atlas": [],
  "cve": [
   "CVE-2026-90898"
  ],
  "ghsa": []
 },
 "primary_asi": "ASI05",
 "agent_framework": "mcp_server",
 "model_provider": "unknown",
 "model_name": "",
 "detection_mechanism": "unknown",
 "tool_access": "unknown",
 "financial_loss_band": "unknown",
 "eai_category": "confused_deputy",
 "eai_domain": "access_control_and_permissions",
 "eai_secondary": [
  "privilege_escalation"
 ],
 "eai_reason": "subcategory: Server-Side Request Forgery via LLM",
 "asi_curated": [],
 "asi_scope": "in_scope",
 "asi_provenance": "rule",
 "asi_reason": "ASI05 (impact=code_exec); ASI03 (eai_category=confused_deputy)",
 "submitted_by": "EAI Internal"
}