CVE-2020-25685 Other in dnsmasq
An off-path attacker can forge DNS replies due to weak hashing, enabling cache poisoning attacks against dnsmasq users.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2020-25685?
CVE-2020-25685 is a low-severity vulnerability in Debian Debian Linux, published on 20 Jan 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-326
Which versions are affected by CVE-2020-25685?
It affects 4 products.
Products include Arista Eos, Debian Debian Linux, Fedoraproject Fedora, Thekelleys Dnsmasq.
How do I fix CVE-2020-25685?
Upgrade to a fixed version.
Is CVE-2020-25685 being exploited?
There is no known exploitation of CVE-2020-25685 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as ALPINE-CVE-2020-25685, CLEANSTART-2026-CW75331, DEBIAN-CVE-2020-25685, GHSA-9gxq-wfg7-72x4, UBUNTU-CVE-2020-25685.