DB_LOOKUP in nss_files/files-XXX.c in the Name Service Switch (NSS) in GNU C Library (aka glibc or libc6) 2.21 and earlier does not properly check if a file is open, which allows remote attackers to cause a denial of service (infinite loop) by performing a look-up on a database while iterating over it, which triggers the file pointer to be reset.
https://security.gentoo.org/glsa/201602-02
http://www.ubuntu.com/usn/USN-2985-2
http://www.ubuntu.com/usn/USN-2985-1
http://www.securityfocus.com/bid/73038
http://www.debian.org/security/2016/dsa-3480
http://rhn.redhat.com/errata/RHSA-2015-0327.html
http://lists.opensuse.org/opensuse-security-announce/2016-02/msg00036.html
http://lists.opensuse.org/opensuse-security-announce/2015-08/msg00019.html