CVE-2020-25684

A flaw was found in dnsmasq before version 2.83. When getting a reply from a forwarded query, dnsmasq checks in the forward.c:reply_query() if the reply destination address/port is used by the pending forwarded queries. However, it does not use the address/port to retrieve the exact forwarded query, substantially reducing the number of attempts an attacker on the network would have to perform to forge a reply and get it accepted by dnsmasq. This issue contrasts with RFC5452, which specifies a query's attributes that all must be used to match a reply. This flaw allows an attacker to perform a DNS Cache Poisoning attack. If chained with CVE-2020-25685 or CVE-2020-25686, the attack complexity of a successful attack is reduced. The highest threat from this vulnerability is to data integrity.

• thekelleys dnsmasq (< 2.83) • fedoraproject fedora 32 • fedoraproject fedora 33 • debian debian linux 9.0 • debian debian linux 10.0 • arista eos (>= 4.21 < 4.21.14m) • arista eos (>= 4.22 < 4.22.9m) • arista eos (>= 4.23 < 4.23.7m) • arista eos (>= 4.24 < 4.24.5m) • arista eos (>= 4.25 < 4.25.2f)