New mozilla-thunderbird packages are available for Slackware 14.1 and -current to fix security issues.

Here are the details from the Slackware 14.1 ChangeLog:
+--------------------------+
patches/packages/mozilla-thunderbird-38.1.0-i486-1_slack14.1.txz: Upgraded.
This release contains security fixes and improvements.
For more information, see:
http://www.mozilla.org/security/known-vulnerabilities/thunderbird.html
(* 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 14.1:
ftp://ftp.slackware.com/pub/slackware/slackware-14.1/patches/packages/mozilla-thunderbird-38.1.0-i486-1_slack14.1.txz

Updated package for Slackware x86_64 14.1:
ftp://ftp.slackware.com/pub/slackware/slackware64-14.1/patches/packages/mozilla-thunderbird-38.1.0-x86_64-1_slack14.1.txz

Updated package for Slackware -current:
ftp://ftp.slackware.com/pub/slackware/slackware-current/slackware/xap/mozilla-thunderbird-38.1.0-i586-1.txz

Updated package for Slackware x86_64 -current:
ftp://ftp.slackware.com/pub/slackware/slackware64-current/slackware64/xap/mozilla-thunderbird-38.1.0-x86_64-1.txz


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

Slackware 14.1 package:
d29cae765dd959599db2dc8fba4fda47 mozilla-thunderbird-38.1.0-i486-1_slack14.1.txz

Slackware x86_64 14.1 package:
0b89334358d130511fd0c2f5d0c40daa mozilla-thunderbird-38.1.0-x86_64-1_slack14.1.txz

Slackware -current package:
020fc71c1e26f9bdccede7e346d2c14c xap/mozilla-thunderbird-38.1.0-i586-1.txz

Slackware x86_64 -current package:
f20699d1a7cf28074a2089c23b431c24 xap/mozilla-thunderbird-38.1.0-x86_64-1.txz


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

Upgrade the package as root:
# upgradepkg mozilla-thunderbird-38.1.0-i486-1_slack14.1.txz


+-----+

Slackware Linux Security Team
http://slackware.com/gpg-key

  Mozilla-thunderbird Update for Slackware