Back to skill

Security audit

AgentMailer Email Router

Security checks for vulnerabilities and agentic risk

Overview

This is a disclosed AgentMailer email routing skill with expected email read/write capabilities and no hidden local code or persistence.

Install only if you intend to let AgentMailer handle mailbox data and user-directed email actions, including drafts, sends, scheduling, labels, and deletions. Use focused read-only or send workflows where possible and require clear confirmation before external sends or destructive mailbox changes.

Vulnerability Patterns
  • Skill Instruction HijackingAlters the agent's session goals or safety constraints when the skill loads
  • Agent Memory PoisoningWrites attacker-controlled rules into memory that affect later sessions
  • Remote Payload Retrieval and ExecutionFetches external code whose behavior can change after review
  • Embedded Malicious CodeShips malicious scripts inside the skill and executes them locally
  • Unauthorized Access and Privilege EscalationObtains permissions beyond the task's legitimate needs
Vulnerability Patterns
  • Data ExfiltrationExternal Transmission, Env Variable Harvesting, File System Enumeration
  • Excessive AgencyUnrestricted Tool Access, Autonomous Decision Making, Scope Creep
  • MCP Tool PoisoningHidden Instructions, Unicode Deception, Parameter Description Injection
  • Prompt InjectionInstruction Override, Hidden Instructions, Exfiltration Commands
  • Privilege EscalationExcessive Permissions, Sudo/Root Execution, Credential Access
Findings (3)

Description-Behavior Mismatch

Medium
Category
Not specified by scanner
Confidence
93% confidence
Finding

The manifest presents this skill as a routing-only component, but it exposes a backend tool capable of reading, drafting, and sending email. That mismatch violates least privilege and can let a supposedly non-mutating router invoke higher-risk operations if routing logic is bypassed, confused, or abused by downstream prompts.

Content

No source excerpt is available for this finding.

External Transmission

Medium
Category
Data Exfiltration
Confidence
50% confidence
Finding

Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.

Content

Scanner excerpt · agents/openai.yaml (reported line 11)May include surrounding context.

yaml
value: "agentmailer"
      description: "Read, draft, and send AgentMailer email"
      transport: "streamable_http"
      url: "https://api.agentmailer.ai/mcp"
policy:
  allow_implicit_invocation: false

Context-Inappropriate Capability

Low
Category
Not specified by scanner
Confidence
88% confidence
Finding

Drafting is broader than the stated purpose of merely routing requests and increases the available action surface unnecessarily. Even if drafting is not as severe as sending, it can expose message content handling, persistence, or preparatory actions that a routing-only skill should not perform.

Content

No source excerpt is available for this finding.

Static analysis

No suspicious patterns detected.