Description of problem:
rkhunter run by cron
SELinux is preventing /usr/bin/mailx from 'append' accesses on the file /var/lib/rkhunter/rkhcronlog.F7vKob6O00.

*****  Plugin restorecon (93.9 confidence) suggests  *************************

If you want to fix the label. 
/var/lib/rkhunter/rkhcronlog.F7vKob6O00 default label should be var_lib_t.
Then you can run restorecon.
Do
# /sbin/restorecon -v /var/lib/rkhunter/rkhcronlog.F7vKob6O00

*****  Plugin leaks (6.10 confidence) suggests  ******************************

If you want to ignore mailx trying to append access the rkhcronlog.F7vKob6O00 file, because you believe it should not need this access.
Then you should report this as a bug.  
You can generate a local policy module to dontaudit this access.
Do
# grep /usr/bin/mailx /var/log/audit/audit.log | audit2allow -D -M mypol
# semodule -i mypol.pp

*****  Plugin catchall (1.43 confidence) suggests  ***************************

If you believe that mailx should be allowed append access on the rkhcronlog.F7vKob6O00 file by default.
Then you should report this as a bug.
You can generate a local policy module to allow this access.
Do
allow this access for now by executing:
# grep mail /var/log/audit/audit.log | audit2allow -M mypol
# semodule -i mypol.pp

Additional Information:
Source Context                system_u:system_r:system_mail_t:s0-s0:c0.c1023
Target Context                system_u:object_r:cron_var_lib_t:s0
Target Objects                /var/lib/rkhunter/rkhcronlog.F7vKob6O00 [ file ]
Source                        mail
Source Path                   /usr/bin/mailx
Port                          <Unknown>
Host                          (removed)
Source RPM Packages           mailx-12.5-7.fc18.x86_64
Target RPM Packages           
Policy RPM                    selinux-policy-3.11.1-67.fc18.noarch
Selinux Enabled               True
Policy Type                   targeted
Enforcing Mode                Enforcing
Host Name                     (removed)
Platform                      Linux (removed) 3.7.2-201.fc18.x86_64 #1 SMP Fri
                              Jan 11 22:16:23 UTC 2013 x86_64 x86_64
Alert Count                   1
First Seen                    2013-01-20 10:19:49 CET
Last Seen                     2013-01-20 10:19:49 CET
Local ID                      d93e3ab0-c789-4ec4-881d-d82c2e31c12f

Raw Audit Messages
type=AVC msg=audit(1358673589.665:686): avc:  denied  { append } for  pid=22030 comm="mail" path="/var/lib/rkhunter/rkhcronlog.F7vKob6O00" dev="dm-2" ino=2622012 scontext=system_u:system_r:system_mail_t:s0-s0:c0.c1023 tcontext=system_u:object_r:cron_var_lib_t:s0 tclass=file


type=SYSCALL msg=audit(1358673589.665:686): arch=x86_64 syscall=execve success=yes exit=0 a0=190d4f0 a1=18bf6f0 a2=153a520 a3=28 items=0 ppid=7363 pid=22030 auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 ses=37 tty=(none) comm=mail exe=/usr/bin/mailx subj=system_u:system_r:system_mail_t:s0-s0:c0.c1023 key=(null)

Hash: mail,system_mail_t,cron_var_lib_t,file,append

audit2allow

#============= system_mail_t ==============
allow system_mail_t cron_var_lib_t:file append;

audit2allow -R

#============= system_mail_t ==============
allow system_mail_t cron_var_lib_t:file append;


Additional info:
hashmarkername: setroubleshoot
kernel:         3.7.2-201.fc18.x86_64
type:           libreport

Potential duplicate: bug 659651