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.

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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
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

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

Type Values Removed Values Added
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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