A pam security update has been released for both CentOS 6 and 7:

CESA-2015:1640 Moderate CentOS 6 pam Security Update
CESA-2015:1640 Moderate CentOS 7 pam Security Update

CESA-2015:1640 Moderate CentOS 6 pam Security Update

CentOS Errata and Security Advisory 2015:1640 Moderate

Upstream details at : https://rhn.redhat.com/errata/RHSA-2015-1640.html

The following updated files have been uploaded and are currently
syncing to the mirrors: ( sha256sum Filename )

i386:
290b2de5b11274bedd3dc14b63bacfc1794b2c4208e4e29979c4c7428eb7964f pam-1.1.1-20.el6_7.1.i686.rpm
6da9c1315ae8d24e44544eed02e3a9fe0c7eece7648bc5b52a3b65a46a86fec8 pam-devel-1.1.1-20.el6_7.1.i686.rpm

x86_64:
290b2de5b11274bedd3dc14b63bacfc1794b2c4208e4e29979c4c7428eb7964f pam-1.1.1-20.el6_7.1.i686.rpm
6c9678f3372acbb5f652c2daf83c1f6ecd80b31b79c2b1b61c333c34a179dcdd pam-1.1.1-20.el6_7.1.x86_64.rpm
6da9c1315ae8d24e44544eed02e3a9fe0c7eece7648bc5b52a3b65a46a86fec8 pam-devel-1.1.1-20.el6_7.1.i686.rpm
a39aae7c68c958278ba676170b8b8b29429cd74618f2dd1b5a7a6886cfa29458 pam-devel-1.1.1-20.el6_7.1.x86_64.rpm

Source:
a47936b7aad2c540af234b821224a9ece34577f1f9e6e94974cc91112e850bde pam-1.1.1-20.el6_7.1.src.rpm

CESA-2015:1640 Moderate CentOS 7 pam Security Update

CentOS Errata and Security Advisory 2015:1640 Moderate

Upstream details at : https://rhn.redhat.com/errata/RHSA-2015-1640.html

The following updated files have been uploaded and are currently
syncing to the mirrors: ( sha256sum Filename )

x86_64:
e0d36e10c6878fa9f1b0b7e9dc15deb22d795925856826ecc8619fd322f23892 pam-1.1.8-12.el7_1.1.i686.rpm
95e6dfc467787bfe47414daa88e9ce701ead0b791e399f891f8cedbce99ff979 pam-1.1.8-12.el7_1.1.x86_64.rpm
d45322823151e2f613dcbe6fb4f30a4c3136c5416a68aeb640c8e3d014c3f1d4 pam-devel-1.1.8-12.el7_1.1.i686.rpm
59ee244c96662c9b7a9a739d88f6a33b8821c3def4ee425cb4d9f98181685508 pam-devel-1.1.8-12.el7_1.1.x86_64.rpm

Source:
a2f8e35f3ab15ebd7821384966adee39e4efaa3cc1fdd0a26b80efdb92301e81 pam-1.1.8-12.el7_1.1.src.rpm