popauth.c in qpopper 4.0.5 and earlier does not properly set the umask, which may cause qpopper to create files with group or world-writable permissions.
http://www.gentoo.org/security/en/glsa/glsa-200505-17.xml
http://www.debian.org/security/2005/dsa-728
http://secunia.com/advisories/15505
http://secunia.com/advisories/15478
http://secunia.com/advisories/15475