CryptoNote version version 0.8.9 and possibly later contain a local RPC server which does not require authentication, as a result the walletd and the simplewallet RPC daemons will process any commands sent to them, resulting in remote command execution and a takeover of the cryptocurrency wallet if an attacker can trick an application such as a web browser into connecting and sending a command for example. This attack appears to be exploitable via a victim visiting a webpage hosting malicious content that trigger such behavior.
https://www.ayrx.me/cryptonote-unauthenticated-json-rpc
https://github.com/cryptonotefoundation/cryptonote/issues/172