Vulnerability Instance

Mitmweb API Authentication Bypass Using Proxy Server
In mitmweb 11.1.0 and below, a malicious client can use mitmweb's proxy server (bound to `*:8080` by default) to access mitmweb's internal API (bound to `127.0.0.1:8081` by default). In other words, while the client cannot access the API directly (good), they can access the API through the proxy (bad). An attacker may be able to escalate this [SSRF](https://en.wikipedia.org/wiki/Server-side_request_forgery)-style access to remote code execution.

The mitmproxy and mitmdump tools are unaffected. Only mitmweb is affected. The `block_global` option, which is enabled by default, blocks connections originating from publicly-routable IP addresses in the proxy. The attacker needs to be in the same local network.