If chained with CVE-2020-25685 or CVE-2020-25686, the attack complexity of a successful attack is reduced. This flaw allows an attacker to perform a DNS Cache Poisoning attack. This issue contrasts with RFC5452, which specifies a query's attributes that all must be used to match a reply. 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. 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. The highest threat from this vulnerability is to data integrity.ДЄ flaw was found in dnsmasq before version 2.83. If chained with CVE-2020-25684, the attack complexity of a successful attack is reduced. This issue is mentioned in the 'Birthday Attacks' section of RFC5452. This flaw allows an off-path attacker on the network to substantially reduce the number of attempts that it would have to perform to forge a reply and have it accepted by dnsmasq. By default, a maximum of 150 pending queries can be sent to upstream servers, so there can be at most 150 queries for the same name. When receiving a query, dnsmasq does not check for an existing pending request for the same name and forwards a new request. If chained with CVE-2020-25684 the attack complexity of a successful attack is reduced. This flaw could be abused to perform a DNS Cache Poisoning attack. This is in contrast with RFC5452, which specifies that the query name is one of the attributes of a query that must be used to match a reply. Due to the weak hash (CRC32 when dnsmasq is compiled without DNSSEC, SHA-1 when it is) this flaw allows an off-path attacker to find several different domains all having the same hash, substantially reducing the number of attempts they would have to perform to forge a reply and get it accepted by dnsmasq. When getting a reply from a forwarded query, dnsmasq checks in forward.c:reply_query(), which is the forwarded query that matches the reply, by only using a weak hash of the query name.

This flaw makes a DNS Cache Poisoning attack much easier. An attacker on the network, able to find the outgoing port used by dnsmasq, only needs to guess the random transmission ID to forge a reply and get it accepted by dnsmasq. When configured to use a specific server for a given network interface, dnsmasq uses a fixed port while forwarding queries. A flaw was found in dnsmasq in versions before 2.85.

Fix cve-2017-14491 for mac