New mozilla-firefox packages are available for 14.2 and -current to fix security issues.

Here are the details from the Slackware 14.2 ChangeLog:
+--------------------------+
patches/packages/mozilla-firefox-60.5.0esr-i686-1_slack14.2.txz: Upgraded.
This release contains security fixes and improvements.
For more information, see:
https://www.mozilla.org/security/known-vulnerabilities/firefoxESR.html
https://www.mozilla.org/en-US/security/advisories/mfsa2019-02/
https://www.mozilla.org/en-US/security/advisories/mfsa2019-02/#CVE-2018-18500
https://www.mozilla.org/en-US/security/advisories/mfsa2019-02/#CVE-2018-18505
https://www.mozilla.org/en-US/security/advisories/mfsa2019-02/#CVE-2018-18501
(* Security fix *)
+--------------------------+


Where to find the new packages:
+-----------------------------+

Thanks to the friendly folks at the OSU Open Source Lab
(http://osuosl.org) for donating FTP and rsync hosting
to the Slackware project!

Also see the "Get Slack" section on http://slackware.com for
additional mirror sites near you.

Updated package for Slackware 14.2:
ftp://ftp.slackware.com/pub/slackware/slackware-14.2/patches/packages/mozilla-firefox-60.5.0esr-i686-1_slack14.2.txz

Updated package for Slackware x86_64 14.2:
ftp://ftp.slackware.com/pub/slackware/slackware64-14.2/patches/packages/mozilla-firefox-60.5.0esr-x86_64-1_slack14.2.txz

Updated package for Slackware -current:
ftp://ftp.slackware.com/pub/slackware/slackware-current/slackware/xap/mozilla-firefox-60.5.0esr-i686-1.txz

Updated package for Slackware x86_64 -current:
ftp://ftp.slackware.com/pub/slackware/slackware64-current/slackware64/xap/mozilla-firefox-60.5.0esr-x86_64-1.txz


MD5 signatures:
+-------------+

Slackware 14.2 package:
cad63204094d15cad52ec6046a3442aa mozilla-firefox-60.5.0esr-i686-1_slack14.2.txz

Slackware x86_64 14.2 package:
6365c7e9317047942266a170327625eb mozilla-firefox-60.5.0esr-x86_64-1_slack14.2.txz

Slackware -current package:
dc6ff398a70e82e215a173645304bd43 xap/mozilla-firefox-60.5.0esr-i686-1.txz

Slackware x86_64 -current package:
4b357a106b675205f173517ea166c392 xap/mozilla-firefox-60.5.0esr-x86_64-1.txz


Installation instructions:
+------------------------+

Upgrade the package as root:
# upgradepkg mozilla-firefox-60.5.0esr-i686-1_slack14.2.txz

  Mozilla-Firefox (SSA:2019-029-01) Updates for Slackware