libuser before 0.56.13-8 and 0.60 before 0.60-7, as used in the userhelper program in the usermode package, directly modifies /etc/passwd, which allows local users to cause a denial of service (inconsistent file state) by causing an error during the modification. NOTE: this issue can be combined with CVE-2015-3245 to gain privileges.
https://www.exploit-db.com/exploits/44633/
https://access.redhat.com/articles/1537873
http://www.securitytracker.com/id/1033040
http://www.securityfocus.com/bid/76022
http://rhn.redhat.com/errata/RHSA-2015-1483.html
http://rhn.redhat.com/errata/RHSA-2015-1482.html
http://lists.opensuse.org/opensuse-security-announce/2015-08/msg00000.html
http://lists.fedoraproject.org/pipermail/package-announce/2015-July/162947.html
http://lists.fedoraproject.org/pipermail/package-announce/2015-August/163044.html