Updated dnsmasq packages has been released for CentOS Linux 6 and 7:

CESA-2017:2836 Critical CentOS 7 dnsmasq Security Update
CESA-2017:2838 Critical CentOS 6 dnsmasq Security Update

CESA-2017:2836 Critical CentOS 7 dnsmasq Security Update

CentOS Errata and Security Advisory 2017:2836 Critical

Upstream details at : https://access.redhat.com/errata/RHSA-2017:2836

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

x86_64:
4116649e1e436cbc3a5cb3f63fab5b4ddd060a3eec2677ef86319abac5fc39a0 dnsmasq-2.76-2.el7_4.2.x86_64.rpm
e6021c48d7461251abf4a6bdbadc493ec435150bc63e57c255196e267fb3e7e1 dnsmasq-utils-2.76-2.el7_4.2.x86_64.rpm

Source:
41f44e7d21c87685a8cfe3558f6cb37f1e87d998e7f5e8bc383e6c3471826443 dnsmasq-2.76-2.el7_4.2.src.rpm

CESA-2017:2838 Critical CentOS 6 dnsmasq Security Update

CentOS Errata and Security Advisory 2017:2838 Critical

Upstream details at : https://access.redhat.com/errata/RHSA-2017:2838

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

i386:
973d0342cc189e8a76a86645b13dddf1582019cb96446f85b68611d8b69249c3 dnsmasq-2.48-18.el6_9.i686.rpm
d97113cf1641a9c46aedd5c4b0d1091ae07ac179e3261334d4bd256186bfbd34 dnsmasq-utils-2.48-18.el6_9.i686.rpm

x86_64:
15647fdea6bbf90bce5b5127dc2da0a0d0b338381dbb73fd1193b7f061986e97 dnsmasq-2.48-18.el6_9.x86_64.rpm
5e62a539a1ab5635ef908109dddb971f68cf476d0efe0475928274f16f207df7 dnsmasq-utils-2.48-18.el6_9.x86_64.rpm

Source:
ddc31b1822ac164af8bdc2f4947f2a760644b1e6c797e6403ef381949ae68109 dnsmasq-2.48-18.el6_9.src.rpm