检查 coremail 用户 user_at_domain 是否存在
AI agents call userExist2 to retrieve information from MCP-YNU FastMCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool performs a simple existence check against a user directory. It queries state without side effects, making it a Read operation. The severity is low because checking user existence is a routine administrative query with minimal blast radius if misused by an AI agent.
From the tool's definition Tool name 'userExist2' and description '检查 coremail 用户 user_at_domain 是否存在' (check if coremail user user_at_domain exists) indicate a query/lookup operation that retrieves existence status without modifying data.
Attacks that exploit this kind of access
检查 coremail 用户 user_at_domain 是否存在. It is categorised as a Read tool in the MCP-YNU FastMCP Server MCP Server, which means it retrieves data without modifying state.
Register the MCP-YNU FastMCP Server MCP server in PolicyLayer and add a rule for userExist2: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches MCP-YNU FastMCP Server. Nothing to install.
userExist2 is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the userExist2 rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for userExist2. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
userExist2 is provided by the MCP-YNU FastMCP Server MCP server (ynu/mcp-ynu). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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