Multiple CRLF injection vulnerabilities in (1) chfn and (2) chsh in shadow 1:4.1.4 allow local users to add new users or groups to /etc/passwd via the GECOS field.
http://secunia.com/advisories/42505
http://secunia.com/advisories/43345
http://slackware.com/security/viewer.php?l=slackware-security&y=2011&m=slackware-security.380014
http://www.debian.org/security/2011/dsa-2164
http://www.securityfocus.com/bid/46426
http://www.ubuntu.com/usn/USN-1065-1
http://www.vupen.com/english/advisories/2011/0396
http://www.vupen.com/english/advisories/2011/0398