All technology depends on technology that has gone before it.
Sometimes the former technology needs to be revisited, to check it is still fit for contemporary purposes.
Such is the case with the WPA2 security protocol, used to encrypt Wi-Fi traffic.
It seems that it has a vulnerability that can be exploited by the ‘KRACK’ attack to decrypt traffic, and in some cases even inject malware into the traffic.
Because the vulnerability is in a protocol that is part of the Wi-Fi specification, it can affect every device that uses Wi-Fi.
Fortunately, this vulnerability was found by researchers, so Wi-Fi equipment makers were made aware of it before it was made public.
Some have already provided fixes for the vulnerability, and some soon will.
However, some equipment will inevitably not get updated, even if the fix exists, so they will be an attack target for years to come.