It was discovered that Tor, an online privacy tool, incorrectly computes buffer sizes in certain cases involving SOCKS connections. Malicious parties could use this to cause a heap-based buffer overflow, potentially allowing execution of arbitrary code. In Tor"s default configuration this issue can only be triggered by clients that can connect to Tor"s socks port, which listens only on localhost by default. In non-default configurations where Tor"s SocksPort listens not only on localhost or where Tor was configured to use another socks server for all of its outgoing connections, Tor is vulnerable to a larger set of malicious parties.