CVE-2020-25685
LOWEPSS 81th pctlDescription
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.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
Exploit Intelligence
Elevated risk: more likely to be exploited than 81% of all known CVEs.
References
Related Vulnerabilities
Other CWE-326 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2014-0224 | High | 7.4 | 95% | - | Fix |
| CVE-2017-1000486 | Critical | 9.8 | 94% | KEV | Fix |
| CVE-2013-2566 | Medium | 5.9 | 84% | - | Fix |
| CVE-2017-11317 | Critical | 9.8 | 83% | KEV | - |
| CVE-2018-18325 | High | 7.5 | 74% | KEV | - |
| CVE-2018-15811 | High | 7.5 | 74% | KEV | - |
Common questions
How do I fix CVE-2020-25685?
Published advisories record a fix for 4 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.
Is CVE-2020-25685 being actively exploited?
Not that we know of. CVE-2020-25685 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 2.2% is the estimated probability that it will be exploited in the next 30 days. That is higher than 81% of all scored CVEs.
How severe is CVE-2020-25685?
CVE-2020-25685 has a CVSS v3 base score of 3.7, rated low. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2020-25685 affect?
Published advisories record a fix for dnsmasq (Debian), dnsmasq (Ubuntu), dnsmasq-base (Ubuntu), dnsmasq-utils (Ubuntu). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-11-04.