PowerDNS Recursor before 3.1.6 does not always use the strongest random number generator for source port selection, which makes it easier for remote attack vectors to conduct DNS cache poisoning. NOTE: this is related to incomplete integration of security improvements associated with addressing CVE-2008-1637.

PowerDNS Recursor before 3.1.5 uses insufficient randomness to calculate (1) TRXID values and (2) UDP source port numbers, which makes it easier for remote attackers to poison a DNS cache, related to (a) algorithmic deficiencies in rand and random functions in external libraries, (b) use of a 32-bit seed value, and (c) choice of the time of day as the sole seeding information.