{
 "public_id": "AIR-2025-0052",
 "incident_id": "2025-07-anthropic-mcp-filesystem-escaperoute",
 "date_disclosed": "2025-07-01",
 "date_occurred": null,
 "title": "EscapeRoute: path-containment and symlink bypasses in Anthropic's Filesystem MCP server (CVE-2025-53110, CVE-2025-53109)",
 "class": "responsible_disclosure",
 "attack_surface": "mcp_server",
 "initial_vector": "prompt_or_tool_argument_controlled_path",
 "agent_capability_abused": [
  "file_read",
  "file_write",
  "symlink_creation"
 ],
 "target_product": "@modelcontextprotocol/server-filesystem",
 "target_vendor": "Anthropic",
 "autonomy_level": "assistant",
 "impact_realized": false,
 "impact_type": [
  "sandbox_escape",
  "arbitrary_file_read",
  "arbitrary_file_write",
  "remote_code_execution",
  "unauthorized_data_access",
  "scope_violation"
 ],
 "blast_radius": "all deployments of Anthropic's reference Filesystem MCP server prior to 2025.7.1; commonly run with the user's full privileges",
 "cve": [
  "CVE-2025-53110",
  "CVE-2025-53109"
 ],
 "taxonomy": {
  "owasp_asi": [
   "ASI05",
   "ASI03"
  ],
  "mitre_atlas": [],
  "labels": [
   "path_traversal",
   "symlink_attack",
   "sandbox_escape",
   "scope_violation",
   "reference_implementation",
   "path_validation",
   "mcp"
  ]
 },
 "defense_present": "allowed-directory allowlist enforced by naive path.startsWith() prefix matching",
 "defense_bypassed": true,
 "fix_shipped": "npm @modelcontextprotocol/server-filesystem 2025.7.1, released 2025-07-01",
 "primary_sources": [
  "https://cymulate.com/blog/cve-2025-53109-53110-escaperoute-anthropic/",
  "https://embracethered.com/blog/posts/2025/anthropic-filesystem-mcp-server-bypass/"
 ],
 "verified_quote": "A naive prefix-matching check lets any path that simply begins with the approved directory (e.g., /private/tmp/allowed_dir) bypass the filter, allowing unrestricted listing, reading and writing outside the intended sandbox.",
 "confidence": "high",
 "notes": "Discovered by Cymulate Research Labs (Elad Beber). CVSS 7.3 (CVE-2025-53110 containment bypass) and 8.4 (CVE-2025-53109 symlink bypass). Reported 2025-03-30, vendor ack 2025-05-01, patched 2025-07-01. Johann Rehberger (embracethered.com) independently documented the directory-prefix bypass. Code execution demonstrated by writing macOS LaunchAgents. Also reported as: 'Anthropic Filesystem MCP server: directory access bypass via startsWith path validation (CVE-2025-53109)'.",
 "risk_category": "security_fraud",
 "risk_secondary": [],
 "risk_subcategory": "Remote Code Execution & Sandbox Escape",
 "risk_sub_secondary": [
  "Over-permissioned execution & lateral movement"
 ],
 "ai_entity": "generative",
 "agency": "agent_acted",
 "agency_debatable": true,
 "agency_reason": "the MCP server read and wrote files outside its sandbox on the agent's behalf",
 "vector_family": "other",
 "vector_detail": "prompt_or_tool_argument_controlled_path",
 "guardrail_kind": [
  "permission_scope"
 ],
 "guardrail_outcome": "silent",
 "xrefs": {
  "aiid": [],
  "atlas": [],
  "cve": [
   "CVE-2025-53110",
   "CVE-2025-53109"
  ],
  "ghsa": []
 },
 "primary_asi": "ASI05",
 "agent_framework": "mcp_server",
 "model_provider": "anthropic",
 "model_name": "",
 "detection_mechanism": "unknown",
 "tool_access": "unknown",
 "financial_loss_band": "unknown",
 "eai_category": "privilege_escalation",
 "eai_domain": "access_control_and_permissions",
 "eai_secondary": [],
 "eai_reason": "subcategory: Remote Code Execution & Sandbox Escape",
 "asi_curated": [],
 "asi_scope": "in_scope",
 "asi_provenance": "rule",
 "asi_reason": "ASI05 (impact=code_exec); ASI03 (signal=identity)",
 "submitted_by": "EAI Internal"
}