{
 "public_id": "AIR-2025-0032",
 "incident_id": "2025-05-mcp-untrusted-servers-confused-clients",
 "date_disclosed": "2025-05-02",
 "date_occurred": null,
 "title": "MCP: untrusted servers and confused clients - tool metadata as a prompt injection channel",
 "class": "responsible_disclosure",
 "attack_surface": "mcp_server",
 "initial_vector": "malicious_tool_description",
 "agent_capability_abused": [
  "tool_metadata_ingestion",
  "tool_invocation"
 ],
 "target_product": "Claude Desktop, GitHub Copilot agent mode, Cursor, ChatGPT AI Actions",
 "target_vendor": "multiple",
 "autonomy_level": "semi_autonomous",
 "impact_realized": false,
 "impact_type": [
  "unauthorized_action",
  "data_exfiltration"
 ],
 "blast_radius": "any client connecting to an untrusted MCP server",
 "cve": [],
 "taxonomy": {
  "owasp_asi": [
   "ASI01",
   "ASI04",
   "ASI03"
  ],
  "mitre_atlas": [],
  "labels": [
   "tool_poisoning",
   "confused_deputy",
   "unicode_tags",
   "mcp"
  ]
 },
 "defense_present": "tool approval UI (does not surface hidden Unicode in tool descriptions)",
 "defense_bypassed": true,
 "fix_shipped": "no fix; disclosed to Anthropic 14+ months earlier and not treated as a security vulnerability",
 "primary_sources": [
  "https://embracethered.com/blog/posts/2025/model-context-protocol-security-risks-and-exploits/"
 ],
 "verified_quote": "Tool calling has its inherent dangers, regardless of the implementation details, be it OpenAPI, AI Actions or MCP - they all suffer from prompt injection and confused deputy threats.",
 "confidence": "high",
 "notes": "Establishes that a malicious MCP server can hijack a conversation even without its tools being invoked.",
 "risk_category": "security_fraud",
 "risk_secondary": [
  "privacy"
 ],
 "risk_subcategory": "Tool & Function Call Extraction / Abuse",
 "risk_sub_secondary": [
  "Prompt Injection"
 ],
 "ai_entity": "generative",
 "agency": "agent_acted",
 "agency_debatable": false,
 "agency_reason": "tool metadata hijacked the client's conversation and tool calls",
 "vector_family": "malicious_component",
 "vector_detail": "malicious_tool_description",
 "guardrail_kind": [
  "human_approval"
 ],
 "guardrail_outcome": "silent",
 "xrefs": {
  "aiid": [],
  "atlas": [],
  "cve": [],
  "ghsa": []
 },
 "primary_asi": "ASI01",
 "agent_framework": "unknown",
 "model_provider": "multiple",
 "model_name": "",
 "detection_mechanism": "external_researcher",
 "tool_access": "unknown",
 "financial_loss_band": "unknown",
 "eai_category": "unsafe_actuation",
 "eai_domain": "agent_behaviour",
 "eai_secondary": [
  "data_exfiltration_channels",
  "confused_deputy",
  "supply_chain_vulnerabilities"
 ],
 "eai_reason": "impact rule: unsafe_actuation",
 "asi_curated": [
  "ASI01"
 ],
 "asi_scope": "in_scope",
 "asi_provenance": "curated_plus_rule",
 "asi_reason": "curated: ASI01 | added ASI04 (vector_family=malicious_component), ASI03 (signal=identity)",
 "submitted_by": "EAI Internal"
}