The OpenSSL QUIC stack contains a feature in which, when using an
already connected socket, it will auto-detect the peer address during the SSL
handshake. This feature uses the getpeername() function, passing a buffer of
sufficient length to hold any supported address family, but passes a buffer
length that is only sized such that larger addresses, such as IPv6, cannot be
retrieved. The getpeername() function however, still returns the full address
length, which is accepted as the valid input buffer length, leading to the
address buffer containing uninitialized stack data instead of the actual peer
address. The invalid peer address is then used as destination for the outgoing
packets which leads to a connectivity breakage and a leakage of the
uninitialized stack data to passive network observers.