Mailbridge — 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": "mailbridge-mcp",
"source": {
"kind": "package",
"origin": "mailbridge-mcp"
},
"server": {
"name": "mailbridge-mcp"
}
},
"grade": "B",
"score": {
"score": 87,
"threatScore": 94,
"grade": "B",
"band": "B",
"categorySubtotals": {
"injection": 6.3,
"exfiltration": 0,
"permissions": 0,
"supply-chain": 0,
"network": 0,
"hygiene": 0
},
"vector": [
{
"kind": "threat",
"ruleId": "MTC-INJ-SCHEMA-1",
"category": "injection",
"severity": "medium",
"confidence": "strong",
"rawWeight": 9,
"confidenceMult": 0.7,
"diminishingFactor": 1,
"appliedPenalty": 6.3
},
{
"kind": "client",
"term": "capability-exposure",
"level": "high",
"label": "capability blast radius (high) — client exposure if the model is manipulated",
"appliedPenalty": 6
},
{
"kind": "client",
"term": "verification-discount",
"level": "repo",
"label": "publisher verification (public source) — no provenance, but the source is public and inspectable",
"appliedPenalty": 1
},
{
"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": "high",
"reasons": [
"ingests untrusted external content (a prompt-injection entry point)",
"can send data / act on an external service",
"can execute shell commands or code"
],
"tags": [
"untrusted-input",
"external-sink",
"code-exec"
]
},
"coverage": {
"level": "source",
"inputs": {
"toolSurface": true,
"implementationSource": true,
"packageMetadata": true,
"liveTransport": false
},
"caveats": [
"Tools were statically extracted from the published source (46 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-SRC-002",
"title": "Shell/command execution in server code (index.js)",
"category": "permissions",
"severity": "high",
"confidence": "strong",
"description": "In the server's implementation (`index.js:7`): 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": "index.js"
},
"evidence": "import { spawn } from 'child_process'; import { dirname } from 'path'; import { fileURLToPath } from 'url'; const __dir",
"owasp": "LLM05:2025 Improper Output Handling",
"data": {
"rule": "MTC-SRC-002",
"file": "index.js",
"line": 7,
"nonRuntime": false
}
},
{
"ruleId": "MTC-FLOW-005",
"title": "Untrusted input can drive an external action",
"category": "exfiltration",
"severity": "medium",
"confidence": "strong",
"description": "Untrusted-input tools ([read_attachment, read_emails, get_emails_with_preview, get_thread, unified_inbox]) co-exist with external-action tools ([send_email]). A prompt injection could cause unwanted external actions, though no direct sensitive-data leak path was found.",
"remediation": "Require confirmation for state-changing/egress actions triggered after processing untrusted content.",
"location": {
"kind": "flow",
"name": "read_attachment → send_email"
},
"evidence": "untrusted [read_attachment, read_emails, get_emails_with_preview, get_thread, unified_inbox] → sinks [send_email]",
"owasp": "LLM06:2025 Excessive Agency",
"references": [],
"data": {
"untrusted": [
"read_attachment",
"read_emails",
"get_emails_with_preview",
"get_thread",
"unified_inbox"
],
"sinks": [
"send_email"
]
}
},
{
"ruleId": "MTC-INJ-SCHEMA-1",
"title": "Description names a credential store the tool cannot reach",
"category": "injection",
"severity": "medium",
"confidence": "strong",
"description": "Tool \"remove_account\" describes a credential store (SSH keys, cloud credentials, a keychain or an equivalent) that nothing in its input schema can address. A tool's interface is the honest statement of what it touches; prose that reaches past it is addressed to the model, not to a reader.",
"remediation": "Remove the reference, or expose the target as an explicit, validated parameter so the client can see and consent to what the tool reads.",
"location": {
"kind": "tool",
"name": "remove_account",
"field": "description"
},
"evidence": "Keychain",
"owasp": "LLM02:2025 Sensitive Information Disclosure",
"data": {}
},
{
"ruleId": "MTC-SRC-002",
"title": "Shell/command execution in packaging/dev tooling (setup.js)",
"category": "permissions",
"severity": "low",
"confidence": "heuristic",
"description": "In a packaging/dev/install script (shipped, but not the server runtime) (`setup.js:10`): 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": "setup.js"
},
"evidence": "port { execSync } from 'child_process'; import { readFileSync, writeFileSync, existsSync } from 'fs'; import { homedir,",
"owasp": "LLM05:2025 Improper Output Handling",
"data": {
"rule": "MTC-SRC-002",
"file": "setup.js",
"line": 10,
"nonRuntime": true
}
},
{
"ruleId": "MTC-SRC-002",
"title": "Shell/command execution in packaging/dev tooling (tools/accounts.js)",
"category": "permissions",
"severity": "low",
"confidence": "heuristic",
"description": "In a packaging/dev/install script (shipped, but not the server runtime) (`tools/accounts.js:4`): 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": "tools/accounts.js"
},
"evidence": "import { spawn } from 'child_process'; import { dirname, join } from 'path'; import { fileURLToPath } from 'url'; impor",
"owasp": "LLM05:2025 Improper Output Handling",
"data": {
"rule": "MTC-SRC-002",
"file": "tools/accounts.js",
"line": 4,
"nonRuntime": true
}
}
],
"toxicFlows": [
{
"id": "flow-1",
"severity": "medium",
"confidence": "strong",
"untrustedInput": [
"read_attachment",
"read_emails",
"get_emails_with_preview",
"get_thread",
"unified_inbox"
],
"sensitiveSource": [],
"externalSink": [
"send_email"
],
"selfContained": false,
"description": "Untrusted input can drive an external action even though no sensitive source is exposed."
}
],
"capabilities": [
{
"tool": "list_accounts",
"tags": [],
"reasons": {}
},
{
"tool": "switch_account",
"tags": [],
"reasons": {}
},
{
"tool": "add_account",
"tags": [],
"reasons": {}
},
{
"tool": "remove_account",
"tags": [],
"reasons": {}
},
{
"tool": "remove_all_accounts",
"tags": [],
"reasons": {}
},
{
"tool": "open_setup",
"tags": [],
"reasons": {}
},
{
"tool": "get_attachments",
"tags": [],
"reasons": {}
},
{
"tool": "read_attachment",
"tags": [
"untrusted-input"
],
"reasons": {
"untrusted-input": [
"keyword \"download\""
]
}
},
{
"tool": "save_draft",
"tags": [],
"reasons": {}
},
{
"tool": "list_drafts",
"tags": [],
"reasons": {}
},
{
"tool": "send_draft",
"tags": [],
"reasons": {}
},
{
"tool": "delete_draft",
"tags": [],
"reasons": {}
},
{
"tool": "schedule_email",
"tags": [],
"reasons": {}
},
{
"tool": "list_scheduled",
"tags": [],
"reasons": {}
},
{
"tool": "cancel_scheduled",
"tags": [],
"reasons": {}
},
{
"tool": "mark_as_read",
"tags": [],
"reasons": {}
},
{
"tool": "mark_as_unread",
"tags": [],
"reasons": {}
},
{
"tool": "move_email",
"tags": [],
"reasons": {}
},
{
"tool": "delete_email",
"tags": [],
"reasons": {}
},
{
"tool": "list_folders",
"tags": [],
"reasons": {}
},
{
"tool": "bulk_mark_read",
"tags": [],
"reasons": {}
},
{
"tool": "bulk_mark_unread",
"tags": [],
"reasons": {}
},
{
"tool": "bulk_move",
"tags": [],
"reasons": {}
},
{
"tool": "bulk_delete",
"tags": [],
"reasons": {}
},
{
"tool": "set_reminder",
"tags": [],
"reasons": {}
},
{
"tool": "list_reminders",
"tags": [],
"reasons": {}
},
{
"tool": "complete_reminder",
"tags": [],
"reasons": {}
},
{
"tool": "unsubscribe_email",
"tags": [],
"reasons": {}
},
{
"tool": "read_emails",
"tags": [
"untrusted-input"
],
"reasons": {
"untrusted-input": [
"keyword \"read_email\""
]
}
},
{
"tool": "get_email_body",
"tags": [],
"reasons": {}
},
{
"tool": "get_emails_with_preview",
"tags": [
"untrusted-input"
],
"reasons": {
"untrusted-input": [
"keyword \"fetch\""
]
}
},
{
"tool": "search_emails",
"tags": [],
"reasons": {}
},
{
"tool": "get_thread",
"tags": [
"untrusted-input"
],
"reasons": {
"untrusted-input": [
"keyword \"fetch\""
]
}
},
{
"tool": "get_contact_history",
"tags": [],
"reasons": {}
},
{
"tool": "unified_inbox",
"tags": [
"untrusted-input"
],
"reasons": {
"untrusted-input": [
"keyword \"fetch\""
]
}
},
{
"tool": "export_email",
"tags": [],
"reasons": {}
},
{
"tool": "extract_calendar_events",
"tags": [],
"reasons": {}
},
{
"tool": "check_email_opens",
"tags": [],
"reasons": {}
},
{
"tool": "list_tracked_emails",
"tags": [],
"reasons": {}
},
{
"tool": "add_rule",
"tags": [],
"reasons": {}
},
{
"tool": "list_rules",
"tags": [],
"reasons": {}
},
{
"tool": "remove_rule",
"tags": [],
"reasons": {}
},
{
"tool": "apply_rules",
"tags": [],
"reasons": {}
},
{
"tool": "send_email",
"tags": [
"external-sink"
],
"reasons": {
"external-sink": [
"keyword \"send_email\""
]
}
},
{
"tool": "reply_to_email",
"tags": [],
"reasons": {}
},
{
"tool": "check_connection",
"tags": [],
"reasons": {}
}
],
"surfaceDigest": "29b1db321c19fbf32fee2fb3663062a397ed295d23d7329a180f63cd53aaf152",
"stats": {
"tools": 46,
"prompts": 0,
"resources": 0,
"findingsBySeverity": {
"critical": 0,
"high": 1,
"medium": 2,
"low": 2,
"info": 0
}
}
}