A flaw was found in dnsmasq before version 2.83. When receiving a query, dnsmasq does not check for an existing pending request for the same name and forwards a new request. 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. 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. This issue is mentioned in the “Birthday Attacks” section of RFC5452. 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.
Source: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-25686
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