Description
A flaw was found in dnsmasq before version 2.83. When getting a reply from a forwarded query, dnsmasq checks in the forward.c:reply_query() if the reply destination address/port is used by the pending forwarded queries. However, it does not use the address/port to retrieve the exact forwarded query, substantially reducing the number of attempts an attacker on the network would have to perform to forge a reply and get it accepted by dnsmasq. This issue contrasts with RFC5452, which specifies a query's attributes that all must be used to match a reply. This flaw allows an attacker to perform a DNS Cache Poisoning attack. If chained with CVE-2020-25685 or CVE-2020-25686, the attack complexity of a successful attack is reduced. The highest threat from this vulnerability is to data integrity.
Published: 2021-01-20
Score: 3.7 Low
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

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Tracking

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Advisories
Source ID Title
Debian DLA Debian DLA DLA-2604-1 dnsmasq security update
Debian DSA Debian DSA DSA-4844-1 dnsmasq security update
EUVD EUVD EUVD-2020-18346 A flaw was found in dnsmasq before version 2.83. When getting a reply from a forwarded query, dnsmasq checks in the forward.c:reply_query() if the reply destination address/port is used by the pending forwarded queries. However, it does not use the address/port to retrieve the exact forwarded query, substantially reducing the number of attempts an attacker on the network would have to perform to forge a reply and get it accepted by dnsmasq. This issue contrasts with RFC5452, which specifies a query's attributes that all must be used to match a reply. This flaw allows an attacker to perform a DNS Cache Poisoning attack. If chained with CVE-2020-25685 or CVE-2020-25686, the attack complexity of a successful attack is reduced. The highest threat from this vulnerability is to data integrity.
Ubuntu USN Ubuntu USN USN-4698-1 Dnsmasq vulnerabilities
History

Tue, 04 Nov 2025 20:30:00 +0000

Type Values Removed Values Added
References

Subscriptions

Arista Eos
Debian Debian Linux
Fedoraproject Fedora
Redhat Enterprise Linux Rhel Aus Rhel E4s Rhel Eus Rhel Tus Rhev Hypervisor
Thekelleys Dnsmasq
cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2025-11-04T19:12:12.109Z

Reserved: 2020-09-16T00:00:00.000Z

Link: CVE-2020-25684

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Modified

Published: 2021-01-20T16:15:14.163

Modified: 2025-11-04T20:15:57.223

Link: CVE-2020-25684

cve-icon Redhat

Severity : Moderate

Publid Date: 2021-01-19T00:00:00Z

Links: CVE-2020-25684 - Bugzilla

cve-icon OpenCVE Enrichment

No data.

Weaknesses