Proton Mail Bridge Client — the complete, unedited output of the deterministic mcptrustchecker engine v1.13.0, scanned . Every finding, capability tag and score component below is exactly what the engine produced — no AI, no post-processing.
{
"tool": {
"name": "mcptrustchecker",
"version": "1.13.0",
"methodologyVersion": "mcptrustchecker-1.13"
},
"target": {
"id": "proton-mail-bridge-client",
"source": {
"kind": "package",
"origin": "proton-mail-bridge-client"
},
"server": {
"name": "proton-mail-bridge-client"
}
},
"grade": "A",
"score": {
"score": 90,
"threatScore": 100,
"grade": "A",
"band": "A",
"categorySubtotals": {
"injection": 0,
"exfiltration": 0,
"permissions": 0,
"supply-chain": 0,
"network": 0,
"hygiene": 0
},
"vector": [
{
"kind": "client",
"term": "capability-exposure",
"level": "critical",
"label": "capability blast radius (critical) — client exposure if the model is manipulated",
"appliedPenalty": 10
},
{
"kind": "client",
"term": "verification-discount",
"level": "source",
"label": "publisher verification (provenance) — cryptographic build provenance ties the artifact to its source",
"appliedPenalty": 0
},
{
"kind": "client",
"term": "coverage-honesty",
"level": "source",
"label": "inspection depth (source) — how much of the target the scan could see",
"appliedPenalty": 0
}
],
"gatesFired": [],
"methodologyVersion": "mcptrustchecker-1.13"
},
"capability": {
"level": "critical",
"reasons": [
"ingests untrusted external content (a prompt-injection entry point)",
"can send data / act on an external service",
"reads sensitive or local data",
"has a read → egress path (a data-exfiltration surface)",
"can execute shell commands or code",
"untrusted-input, sensitive-source and egress co-exist across tools (toxic-flow surface)",
"untrusted input can reach code execution"
],
"tags": [
"external-sink",
"untrusted-input",
"sensitive-source",
"code-exec"
]
},
"coverage": {
"level": "source",
"inputs": {
"toolSurface": true,
"implementationSource": true,
"packageMetadata": true,
"liveTransport": false
},
"caveats": [
"Tools were statically extracted from the published source (96 recovered), not enumerated from a running server. Tool-poisoning, Unicode-smuggling, capability and toxic-flow analysis ran on this inferred surface, but a mis-parsed registration could be missed or mis-attributed, so tool-derived findings are capped below “confirmed”. To grade the real runtime surface, scan the running server: --command \"npx -y <package>\"."
]
},
"findings": [
{
"ruleId": "MTC-FLOW-002",
"title": "Completed toxic-flow trifecta across tools",
"category": "exfiltration",
"severity": "critical",
"confidence": "strong",
"description": "This server (without client built-ins) exposes a complete data-exfiltration chain: export_email → get_audit_logs → cancel_send. Untrusted input is ingested, private data is read, and it can be sent to an external sink via the agent composing the tools (→). Static analysis proves the primitive exists, not that a specific run will occur.",
"remediation": "Remove one leg of the trifecta: isolate untrusted-input tools from secret-reading tools and from egress tools, or require human approval between them.",
"location": {
"kind": "flow",
"name": "export_email → get_audit_logs → cancel_send"
},
"owasp": "LLM02:2025 Sensitive Information Disclosure",
"references": [],
"data": {
"untrusted": [
"get_draft",
"get_emails",
"get_email_by_id",
"get_emails_by_ids",
"get_folders",
"prepare_meeting_context",
"get_thread_by_id",
"list_attachments",
"get_attachment_content",
"save_attachments",
"export_email"
],
"sources": [
"get_logs",
"get_audit_logs"
],
"sinks": [
"send_email",
"cancel_send",
"list_scheduled_sends",
"send_test_email",
"forward_email",
"create_forward_draft",
"render_template"
],
"path": [
"export_email",
"get_audit_logs",
"cancel_send"
],
"edges": [
{
"from": "export_email",
"to": "get_audit_logs",
"kind": "agent-mediated"
},
{
"from": "get_audit_logs",
"to": "cancel_send",
"kind": "agent-mediated"
}
],
"wired": false
}
},
{
"ruleId": "MTC-SRC-002",
"title": "Shell/command execution in server code (dist/cli.js)",
"category": "permissions",
"severity": "high",
"confidence": "strong",
"description": "In the server's implementation (`dist/cli.js:2`): Spawning a shell/process is command-execution capability; with unsanitized tool input it is command injection / RCE. This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.",
"remediation": "Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.",
"location": {
"kind": "server",
"name": "dist/cli.js"
},
"evidence": "{ execFile } from \"node:child_process\"; import { readFile } from \"node:fs/promises\"; import { promisify } from \"node:uti",
"owasp": "LLM05:2025 Improper Output Handling",
"data": {
"rule": "MTC-SRC-002",
"file": "dist/cli.js",
"line": 2,
"nonRuntime": false
}
},
{
"ruleId": "MTC-SRC-002",
"title": "Shell/command execution in server code (dist/index.js)",
"category": "permissions",
"severity": "high",
"confidence": "strong",
"description": "In the server's implementation (`dist/index.js:2`): Spawning a shell/process is command-execution capability; with unsanitized tool input it is command injection / RCE. This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.",
"remediation": "Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.",
"location": {
"kind": "server",
"name": "dist/index.js"
},
"evidence": "ecFileSync } from \"node:child_process\"; import { readFileSync } from \"node:fs\"; import { createRequire } from \"node:modu",
"owasp": "LLM05:2025 Improper Output Handling",
"data": {
"rule": "MTC-SRC-002",
"file": "dist/index.js",
"line": 2,
"nonRuntime": false
}
},
{
"ruleId": "MTC-SRC-002",
"title": "Shell/command execution in packaging/dev tooling (dist/scripts/install-claude-desktop.js)",
"category": "permissions",
"severity": "low",
"confidence": "heuristic",
"description": "In a packaging/dev/install script (shipped, but not the server runtime) (`dist/scripts/install-claude-desktop.js:1`): Spawning a shell/process is command-execution capability; with unsanitized tool input it is command injection / RCE. This is read from the code itself — not from the tool description — so a poisoned server cannot hide it behind honest-looking metadata.",
"remediation": "Review this call path: confirm it never receives unsanitized tool input, constrain it, or remove it. Treat a server whose code reaches these sinks as high-capability regardless of what its tools claim.",
"location": {
"kind": "server",
"name": "dist/scripts/install-claude-desktop.js"
},
"evidence": "{ execFile } from \"node:child_process\"; import { constants as fsConstants, realpathSync } from \"node:fs\"; import { acces",
"owasp": "LLM05:2025 Improper Output Handling",
"data": {
"rule": "MTC-SRC-002",
"file": "dist/scripts/install-claude-desktop.js",
"line": 1,
"nonRuntime": true
}
}
],
"toxicFlows": [
{
"id": "flow-1",
"severity": "critical",
"confidence": "strong",
"untrustedInput": [
"get_draft",
"get_emails",
"get_email_by_id",
"get_emails_by_ids",
"get_folders",
"prepare_meeting_context",
"get_thread_by_id",
"list_attachments",
"get_attachment_content",
"save_attachments",
"export_email"
],
"sensitiveSource": [
"get_logs",
"get_audit_logs"
],
"externalSink": [
"send_email",
"cancel_send",
"list_scheduled_sends",
"send_test_email",
"forward_email",
"create_forward_draft",
"render_template"
],
"selfContained": false,
"path": [
"export_email",
"get_audit_logs",
"cancel_send"
],
"pathWired": false,
"description": "A cross-tool exfiltration chain exists: export_email → get_audit_logs → cancel_send."
}
],
"capabilities": [
{
"tool": "send_email",
"tags": [
"external-sink"
],
"reasons": {
"external-sink": [
"keyword \"send_email\""
]
}
},
{
"tool": "cancel_send",
"tags": [
"external-sink"
],
"reasons": {
"external-sink": [
"keyword \"send_email\""
]
}
},
{
"tool": "list_scheduled_sends",
"tags": [
"external-sink"
],
"reasons": {
"external-sink": [
"keyword \"send_email\""
]
}
},
{
"tool": "get_unsubscribe_info",
"tags": [],
"reasons": {}
},
{
"tool": "unsubscribe_sender",
"tags": [],
"reasons": {}
},
{
"tool": "send_test_email",
"tags": [
"external-sink"
],
"reasons": {
"external-sink": [
"keyword \"send_email\""
]
}
},
{
"tool": "reply_to_email",
"tags": [],
"reasons": {}
},
{
"tool": "reply_all_email",
"tags": [],
"reasons": {}
},
{
"tool": "forward_email",
"tags": [
"external-sink"
],
"reasons": {
"external-sink": [
"keyword \"forward_email\""
]
}
},
{
"tool": "create_draft",
"tags": [],
"reasons": {}
},
{
"tool": "create_reply_draft",
"tags": [],
"reasons": {}
},
{
"tool": "create_forward_draft",
"tags": [
"external-sink"
],
"reasons": {
"external-sink": [
"keyword \"forward_email\""
]
}
},
{
"tool": "list_drafts",
"tags": [],
"reasons": {}
},
{
"tool": "list_remote_drafts",
"tags": [],
"reasons": {}
},
{
"tool": "get_draft",
"tags": [
"untrusted-input"
],
"reasons": {
"untrusted-input": [
"keyword \"fetch\""
]
}
},
{
"tool": "update_draft",
"tags": [],
"reasons": {}
},
{
"tool": "sync_draft_to_remote",
"tags": [],
"reasons": {}
},
{
"tool": "send_draft",
"tags": [],
"reasons": {}
},
{
"tool": "schedule_draft",
"tags": [],
"reasons": {}
},
{
"tool": "delete_draft",
"tags": [],
"reasons": {}
},
{
"tool": "get_emails",
"tags": [
"untrusted-input"
],
"reasons": {
"untrusted-input": [
"keyword \"fetch\""
]
}
},
{
"tool": "get_email_by_id",
"tags": [
"untrusted-input"
],
"reasons": {
"untrusted-input": [
"keyword \"fetch\""
]
}
},
{
"tool": "get_emails_by_ids",
"tags": [
"untrusted-input"
],
"reasons": {
"untrusted-input": [
"keyword \"fetch\""
]
}
},
{
"tool": "search_emails",
"tags": [],
"reasons": {}
},
{
"tool": "get_folders",
"tags": [
"untrusted-input"
],
"reasons": {
"untrusted-input": [
"keyword \"fetch\""
]
}
},
{
"tool": "sync_folders",
"tags": [],
"reasons": {}
},
{
"tool": "create_folder",
"tags": [],
"reasons": {}
},
{
"tool": "rename_folder",
"tags": [],
"reasons": {}
},
{
"tool": "delete_folder",
"tags": [],
"reasons": {}
},
{
"tool": "mark_email_read",
"tags": [],
"reasons": {}
},
{
"tool": "star_email",
"tags": [],
"reasons": {}
},
{
"tool": "move_email",
"tags": [],
"reasons": {}
},
{
"tool": "archive_email",
"tags": [],
"reasons": {}
},
{
"tool": "trash_email",
"tags": [],
"reasons": {}
},
{
"tool": "restore_email",
"tags": [],
"reasons": {}
},
{
"tool": "snooze_email",
"tags": [],
"reasons": {}
},
{
"tool": "cancel_snooze",
"tags": [],
"reasons": {}
},
{
"tool": "list_snoozed",
"tags": [],
"reasons": {}
},
{
"tool": "create_template",
"tags": [],
"reasons": {}
},
{
"tool": "list_templates",
"tags": [],
"reasons": {}
},
{
"tool": "get_template",
"tags": [],
"reasons": {}
},
{
"tool": "delete_template",
"tags": [],
"reasons": {}
},
{
"tool": "render_template",
"tags": [
"external-sink"
],
"reasons": {
"external-sink": [
"keyword \"send_email\""
]
}
},
{
"tool": "delete_email",
"tags": [],
"reasons": {}
},
{
"tool": "update_message_labels",
"tags": [],
"reasons": {}
},
{
"tool": "update_message_flags",
"tags": [],
"reasons": {}
},
{
"tool": "count_messages",
"tags": [],
"reasons": {}
},
{
"tool": "folder_stats",
"tags": [],
"reasons": {}
},
{
"tool": "empty_folder",
"tags": [],
"reasons": {}
},
{
"tool": "bulk_move",
"tags": [],
"reasons": {}
},
{
"tool": "bulk_delete",
"tags": [],
"reasons": {}
},
{
"tool": "bulk_update_flags",
"tags": [],
"reasons": {}
},
{
"tool": "bulk_update_labels",
"tags": [],
"reasons": {}
},
{
"tool": "top_senders",
"tags": [],
"reasons": {}
},
{
"tool": "move_thread",
"tags": [],
"reasons": {}
},
{
"tool": "delete_thread",
"tags": [],
"reasons": {}
},
{
"tool": "flag_thread",
"tags": [],
"reasons": {}
},
{
"tool": "create_label",
"tags": [],
"reasons": {}
},
{
"tool": "rename_label",
"tags": [],
"reasons": {}
},
{
"tool": "delete_label",
"tags": [],
"reasons": {}
},
{
"tool": "batch_email_action",
"tags": [],
"reasons": {}
},
{
"tool": "apply_thread_action",
"tags": [],
"reasons": {}
},
{
"tool": "get_email_stats",
"tags": [],
"reasons": {}
},
{
"tool": "get_email_analytics",
"tags": [],
"reasons": {}
},
{
"tool": "get_contacts",
"tags": [],
"reasons": {}
},
{
"tool": "get_volume_trends",
"tags": [],
"reasons": {}
},
{
"tool": "get_connection_status",
"tags": [],
"reasons": {}
},
{
"tool": "get_runtime_status",
"tags": [],
"reasons": {}
},
{
"tool": "run_doctor",
"tags": [],
"reasons": {}
},
{
"tool": "run_background_sync",
"tags": [],
"reasons": {}
},
{
"tool": "wait_for_mailbox_changes",
"tags": [],
"reasons": {}
},
{
"tool": "sync_emails",
"tags": [],
"reasons": {}
},
{
"tool": "get_index_status",
"tags": [],
"reasons": {}
},
{
"tool": "search_indexed_emails",
"tags": [],
"reasons": {}
},
{
"tool": "get_labels",
"tags": [],
"reasons": {}
},
{
"tool": "get_threads",
"tags": [],
"reasons": {}
},
{
"tool": "get_actionable_threads",
"tags": [],
"reasons": {}
},
{
"tool": "get_inbox_digest",
"tags": [],
"reasons": {}
},
{
"tool": "get_follow_up_candidates",
"tags": [],
"reasons": {}
},
{
"tool": "find_document_threads",
"tags": [],
"reasons": {}
},
{
"tool": "prepare_meeting_context",
"tags": [
"untrusted-input"
],
"reasons": {
"untrusted-input": [
"keyword \"fetch\""
]
}
},
{
"tool": "get_thread_brief",
"tags": [],
"reasons": {}
},
{
"tool": "get_thread_by_id",
"tags": [
"untrusted-input"
],
"reasons": {
"untrusted-input": [
"keyword \"fetch\""
]
}
},
{
"tool": "create_thread_reply_draft",
"tags": [],
"reasons": {}
},
{
"tool": "list_attachments",
"tags": [
"untrusted-input"
],
"reasons": {
"untrusted-input": [
"keyword \"download\""
]
}
},
{
"tool": "get_attachment_content",
"tags": [
"untrusted-input"
],
"reasons": {
"untrusted-input": [
"keyword \"fetch\""
]
}
},
{
"tool": "get_attachment_text",
"tags": [],
"reasons": {}
},
{
"tool": "save_attachments",
"tags": [
"untrusted-input"
],
"reasons": {
"untrusted-input": [
"keyword \"download\""
]
}
},
{
"tool": "save_attachment",
"tags": [],
"reasons": {}
},
{
"tool": "export_email",
"tags": [
"untrusted-input"
],
"reasons": {
"untrusted-input": [
"keyword \"download\""
]
}
},
{
"tool": "import_email",
"tags": [],
"reasons": {}
},
{
"tool": "clear_cache",
"tags": [],
"reasons": {}
},
{
"tool": "clear_index",
"tags": [],
"reasons": {}
},
{
"tool": "get_logs",
"tags": [
"sensitive-source"
],
"reasons": {
"sensitive-source": [
"keyword \"get_logs\""
]
}
},
{
"tool": "get_audit_logs",
"tags": [
"sensitive-source"
],
"reasons": {
"sensitive-source": [
"keyword \"get_logs\""
]
}
},
{
"tool": "proton-mail-bridge-client",
"tags": [],
"reasons": {}
}
],
"surfaceDigest": "636de5f8ec1e843c1e30ee0526e8d5693d98e1028f9b599a5bdca6fe73de0466",
"stats": {
"tools": 96,
"prompts": 0,
"resources": 0,
"findingsBySeverity": {
"critical": 1,
"high": 2,
"medium": 0,
"low": 1,
"info": 0
}
}
}