CVE-2020-25686
LOWEPSS 92th pctlDescription
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.
How to fix
This Ubuntu release reached end-of-life on 2023-05-31. Extended security maintenance is available until 2028-04-01.
This Ubuntu release reached end-of-life on 2025-05-31. Extended security maintenance is available until 2030-04-02.
This Ubuntu release reached end-of-life on 2023-05-31. Extended security maintenance is available until 2028-04-01.
This Ubuntu release reached end-of-life on 2025-05-31. Extended security maintenance is available until 2030-04-02.
This Ubuntu release reached end-of-life on 2023-05-31. Extended security maintenance is available until 2028-04-01.
This Ubuntu release reached end-of-life on 2025-05-31. Extended security maintenance is available until 2030-04-02.
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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
High risk: more likely to be exploited than 92% of all known CVEs.
References
Related Vulnerabilities
Other CWE-358 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2018-1270 | Critical | 9.8 | 77% | - | Fix |
| CVE-2018-1275 | Critical | 9.8 | 58% | - | Fix |
| CVE-2024-7965 | High | 8.8 | 19% | KEV | Fix |
| CVE-2017-15663 | High | 7.5 | 13% | - | - |
| CVE-2016-10229 | Critical | 9.8 | 13% | - | Fix |
| CVE-2024-2174 | High | 8.8 | 13% | - | Fix |
Common questions
How do I fix CVE-2020-25686?
Published advisories record a fix for 7 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-2020-25686 being actively exploited?
Not that we know of. CVE-2020-25686 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 4.9% is the estimated probability that it will be exploited in the next 30 days. That is higher than 92% of all scored CVEs.
How severe is CVE-2020-25686?
CVE-2020-25686 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-2020-25686 affect?
Published advisories record a fix for dnsmasq (Amazon), dnsmasq-debuginfo (Amazon), dnsmasq-utils (Amazon), dnsmasq (Debian), and 3 more. 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 2026-06-17.