Chrome 63.0.3239.132
AFAIK this does not address the Meltdown and Spectre stuff. That was due to happen with Chrome 64 due out next Tuesday.
“The stable channel has been updated to 63.0.3239.132 for Windows, Mac and Linux”
Download
Firefox 54.0.4
“Security fixes to address the Meltdown and Spectre timing attacks”
Download
Release Notes
It is Firefox 57.0.4, not 54.0.3.
Thanks