CVE-2020-25685

A flaw was found in dnsmasq before version 2.83. 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. 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. 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. This flaw could be abused to perform a DNS Cache
Poisoning attack. If chained with CVE-2020-25684 the attack complexity of a
successful attack is reduced. The highest threat from this vulnerability is
to data integrity.