When using `pw -V ...`, if either master.passwd or group contains erroneous data then pw will segfault. e.g. as a result of hand editing. Also could be a continuation of bug #187310.

To reproduce execute the following in an empty directory:

truncate -s 0 master.passwd group && pwd_mkdb -d . master.passwd
pw -V . user add test
echo 'test1:*:1002:0:0::/home/test1' >> master.passwd
pw -V . user add test2
Segmentation fault (core dumped)

Similarly for group:

truncate -s 0 master.passwd group && pwd_mkdb -d . master.passwd
pw -V . user add test
echo 'test1:*:1002' >> group
pw -V . user add test2
Segmentation fault (core dumped)

It doesn't matter what pw -V command  you run, if it accesses an erroneous master.passwd/group it segfaults.

I first came across it in:
FreeBSD 10.1-STABLE #0 r279301: Wed Feb 25 23:49:09 UTC 2015 amd64
and have since updated to r279937

The following fixes the segfaults, but could lead to other issues as the erroneous entries are simply ignored.

Index: usr.sbin/pw/pw_vpw.c
===================================================================
--- usr.sbin/pw/pw_vpw.c	(revision 279937)
+++ usr.sbin/pw/pw_vpw.c	(working copy)
@@ -80,6 +80,9 @@
 			if (line[linelen - 1 ] == '\n')
 				line[linelen - 1] = '\0';
 			pw = pw_scan(line, PWSCAN_MASTER);
+			/* Skip erroneous lines... maybe warn? */
+			if (pw == NULL)
+			    continue;
 			if (uid != (uid_t)-1) {
 				if (uid == pw->pw_uid)
 					break;
@@ -160,6 +163,9 @@
 			if (line[linelen - 1 ] == '\n')
 				line[linelen - 1] = '\0';
 			gr = gr_scan(line);
+			/* Skip erroneous lines.. maybe warn? */
+			if (gr == NULL)
+			    continue;
 			if (gid != (gid_t)-1) {
 				if (gid == gr->gr_gid)
 					break;