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.
Source: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-25684
Reference (s):
- DEBIAN:DSA-4844
- URL: https://www.debian.org/security/2021/dsa-4844
- FEDORA:FEDORA-2021-2e4c3d5a9d
- URL: https://lists.fedoraproject.org/archives/list/[email protected]/message/QGB7HL3OWHTLEPSMLDGOMXQKG3KM2QME/
- FEDORA:FEDORA-2021-84440e87ba