CURL-CVE-2022-30115

HSTS bypass via trailing dot

curl's HSTS check could be bypassed to trick it to keep using HTTP. Using its HSTS support, curl can be instructed to use HTTPS directly instead of using an insecure clear-text HTTP step even when HTTP is provided in the URL. This mechanism could be bypassed if the hostname in the given URL used a trailing dot while not using one when it built the HSTS cache. Or the other way around - by having the trailing dot in the HSTS cache and *not* using the trailing dot in the URL. Since trailing dots in hostnames are somewhat special, many sites work equally fine with or without a trailing dot present.