bitcoind and Bitcoin-Qt prior to 0.15.1 have a stack-based buffer overflow if an attacker-controlled SOCKS proxy server is used. This results from an integer signedness error when the proxy server responds with an acknowledgement of an unexpected target domain name.
https://medium.com/%40lukedashjr/cve-2017-18350-disclosure-fe6d695f45d5
https://en.bitcoin.it/wiki/Common_Vulnerabilities_and_Exposures