There is a MEDIUM severity vulnerability affecting CPython. The “socket” module provides a pure-Python fallback to the socket.socketpair() function for platforms that don’t support AFUNIX, such as Windows. This pure-Python implementation uses AFINET or AFINET6 to create a local connected pair of sockets. The connection between the two sockets was not verified before passing the two sockets back to the user, which leaves the server socket vulnerable to a connection race from a malicious local peer. Platforms that support AFUNIX such as Linux and macOS are not affected by this vulnerability. Versions prior to CPython 3.5 are not affected due to the vulnerable API not being included.