CVE & CISA-KEV Catalog

CVE-2020-25686

LOWEPSS 91th pctl
3.7
CVSS v3
NVD

Description

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.

CWE-358CWE-290

How to fix

Remediation Available
dnsmasqDebian
Fixed in:2.83-1CVE-2020-25686
Fixed in:2.83-1CVE-2020-25686
Fixed in:2.83-1CVE-2020-25686
Fixed in:2.83-1CVE-2020-25686
dnsmasqUbuntu
Fixed in:2.75-1ubuntu0.16.04.7USN-4698-1
Fixed in:2.79-1ubuntu0.2USN-4698-1
Fixed in:2.80-1.1ubuntu1.2USN-4698-1
dnsmasq-baseUbuntu
Fixed in:2.75-1ubuntu0.16.04.7USN-4698-1
Fixed in:2.79-1ubuntu0.2USN-4698-1
Fixed in:2.80-1.1ubuntu1.2USN-4698-1
dnsmasq-utilsUbuntu
Fixed in:2.75-1ubuntu0.16.04.7USN-4698-1
Fixed in:2.79-1ubuntu0.2USN-4698-1
Fixed in:2.80-1.1ubuntu1.2USN-4698-1

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

Attack VectorNetwork
Attack ComplexityHigh
Privileges RequiredNone
User InteractionNone
ScopeUnchanged

Impact

ConfidentialityNone
IntegrityLow
AvailabilityNone

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

Exploit Intelligence

4.87%probability of exploitation in 30 days
91stpercentile

High risk: more likely to be exploited than 91% of all known CVEs.

References

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Markdown

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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.