You can download and install the latest Firefox 58 beta which fixes several vulnerabilities including Meltdown and Spectre timing attacks through the web browser.
Some information :
https://blog.mozilla.org/security/2018/01/03/mitigations-landing-new-class-timing-attack/
https://www.mozilla.org/en-US/security/advisories/mfsa2018-01/
I just built a binary package, available here : mozilla-firefox-58.0b14-x86_64-180105.txz
Package works for Zenwalk and, of course : Slackware.
All the best
JP
