CVE-2023-38545

This flaw makes curl overflow a heap based buffer in the SOCKS5 proxy
handshake. When curl is asked to pass along the host name to the SOCKS5
proxy to allow that to resolve the address instead of it getting done by
curl itself, the maximum length that host name can be is 255 bytes. If the
host name is detected to be longer, curl switches to local name resolving
and instead passes on the resolved address only. Due to this bug, the local
variable that means “let the host resolve the name” could get the wrong
value during a slow SOCKS5 handshake, and contrary to the intention, copy
the too long host name to the target buffer instead of copying just the
resolved address there. The target buffer being a heap based buffer, and
the host name coming from the URL that curl has been told to operate with.

Notes