New gd packages are available for Slackware 14.2 and -current to fix security issues.

Here are the details from the Slackware 14.2 ChangeLog:
+--------------------------+
This update fixes two security issues:
Double-free in gdImagePngPtr() (denial of service).
Buffer over-read into uninitialized memory (information leak).
For more information, see:
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-6362
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-7890
(* 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/gd-2.2.5-i586-1_slack14.2.txz

Updated package for Slackware x86_64 14.2:
ftp://ftp.slackware.com/pub/slackware/slackware64-14.2/patches/packages/gd-2.2.5-x86_64-1_slack14.2.txz

Updated package for Slackware -current:
ftp://ftp.slackware.com/pub/slackware/slackware-current/slackware/l/gd-2.2.5-i586-1.txz

Updated package for Slackware x86_64 -current:
ftp://ftp.slackware.com/pub/slackware/slackware64-current/slackware64/l/gd-2.2.5-x86_64-1.txz


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

Slackware 14.2 package:
00f7ac709aebd7e2d83c106496a67503 gd-2.2.5-i586-1_slack14.2.txz

Slackware x86_64 14.2 package:
55090c6941dea831bdc6ad78d47055d9 gd-2.2.5-x86_64-1_slack14.2.txz

Slackware -current package:
c996a52a4eed3ccc5af79320d27ef9f8 l/gd-2.2.5-i586-1.txz

Slackware x86_64 -current package:
e9a5c2882717f1df8d25c7b1ae03ecb5 l/gd-2.2.5-x86_64-1.txz


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

Upgrade the package as root:
# upgradepkg gd-2.2.5-i586-1_slack14.2.txz

  GD Update (SSA:2018-108-01) for Slackware