A format string vulnerability
in the foreign_option function in options.c could
potentially allow a malicious or compromised server
to execute arbitrary code on the client. Only
non-Windows clients are affected. The vulnerability
only exists if (a) the client's TLS negotiation with
the server succeeds, (b) the server is malicious or
has been compromised such that it is configured to
push a maliciously crafted options string to the client,
and (c) the client indicates its willingness to accept
pushed options from the server by having "pull" or
"client" in its configuration file (Credit: Vade79).