AI agents call extract_session_variable to retrieve information from Mitmproxy without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Extracting session variables from HTTP traffic is a Read operation—it queries or retrieves existing data without modification. However, severity is medium rather than low because session variables often contain sensitive authentication tokens, cookies, or user credentials that could enable account compromise if exposed to a malicious agent.
From the tool's definition Tool name 'extract_session_variable' and server context indicate retrieval of session data from intercepted traffic. The mitmproxy-mcp server description emphasizes 'inspect' and 'real-time' traffic examination.
Documented attack patterns abuse exactly the kind of access extract_session_variable gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Mitmproxy, and nothing reaches the server without passing your rules. This is the rule we recommend for extract_session_variable:
{
"version": "1",
"default": "deny",
"tools": {
"extract_session_variable": {}
}
}extract_session_variable is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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extract_session_variable. It is categorised as a Read tool in the Mitmproxy MCP Server, which means it retrieves data without modifying state.
Register the Mitmproxy MCP server in PolicyLayer and add a rule for extract_session_variable: 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 Mitmproxy. Nothing to install.
extract_session_variable 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 extract_session_variable 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 extract_session_variable. 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.
extract_session_variable is provided by the Mitmproxy MCP server (snapspecter/mitmproxy-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 25 Mitmproxy tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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25 Mitmproxy tools catalogued and risk-classified — across an index of 42,500+ MCP servers.