After an upgrading with yum program, yum will end with segmentation fault.

Last link about libz is the cause:

-rwxr-xr-x 1 root root  75028  9 gen  2007 libz.so.1.2.3
-rwxr-xr-x 1 root bin   96572  8 nov  2010 libz.so.1.2.5
-rw-r–r– 1 root bin  101462  8 nov  2010 libz.a
lrwxrwxrwx 1 root root     13  8 apr  2011 libz.so -> libz.so.1.2.3
lrwxrwxrwx 1 root root     13  8 apr  2011 libz.so.1 -> libz.so.1.2.5

libz.so.1 need a different link:

lrwxrwxrwx 1 root root     13  8 apr  2011 libz.so.1 -> libz.so.1.2.3

Reference: yum fails with segfault after source zlib upgrade