c-ares before 1.4.0 uses a predictable seed for the random number generator for the DNS Transaction ID field, which might allow remote attackers to spoof DNS responses by guessing the field value.
https://exchange.xforce.ibmcloud.com/vulnerabilities/34979
http://www.securityfocus.com/bid/24386
http://secunia.com/advisories/25579
http://cool.haxx.se/cvs.cgi/curl/ares/CHANGES?rev=HEAD&content-type=text/vnd.viewcvs-markup