CVE-2020-25685 A flaw was found in dnsmasq before version 2.83
Description
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.
Affected products and versions
| Product | Affected versions | Fixed in |
|---|---|---|
| dnsmasq | Versions not published |
References
- www.jsof-tech.com www.jsof-tech.com
- bugzilla.redhat.com bugzilla.redhat.com
- FEDORA-2021-84440e87ba lists.fedoraproject.org
- GLSA-202101-17 security.gentoo.org
- DSA-4844 www.debian.org
- FEDORA-2021-2e4c3d5a9d lists.fedoraproject.org
- www.arista.com www.arista.com
Timeline
- Published
- Last modified