CVE-2020-25687

5.9 MEDIUM
Published: January 20, 2021 Modified: November 04, 2025

Description

A flaw was found in dnsmasq before version 2.83. A heap-based buffer overflow was discovered in dnsmasq when DNSSEC is enabled and before it validates the received DNS entries. This flaw allows a remote attacker, who can create valid DNS replies, to cause an overflow in a heap-allocated memory. This flaw is caused by the lack of length checks in rfc1035.c:extract_name(), which could be abused to make the code execute memcpy() with a negative size in sort_rrset() and cause a crash in dnsmasq, resulting in a denial of service. The highest threat from this vulnerability is to system availability.

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1891568
Source: secalert@redhat.com
Issue Tracking Patch Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/03/msg00027.html
Source: secalert@redhat.com
Mailing List Third Party Advisory
https://security.gentoo.org/glsa/202101-17
Source: secalert@redhat.com
Third Party Advisory
https://www.debian.org/security/2021/dsa-4844
Source: secalert@redhat.com
Third Party Advisory
https://www.jsof-tech.com/disclosures/dnspooq/
Source: secalert@redhat.com
Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1891568
Source: af854a3a-2127-422b-91ae-364da2661108
Issue Tracking Patch Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/03/msg00027.html
Source: af854a3a-2127-422b-91ae-364da2661108
Mailing List Third Party Advisory
https://security.gentoo.org/glsa/202101-17
Source: af854a3a-2127-422b-91ae-364da2661108
Third Party Advisory
https://www.debian.org/security/2021/dsa-4844
Source: af854a3a-2127-422b-91ae-364da2661108
Third Party Advisory
https://www.jsof-tech.com/disclosures/dnspooq/
Source: af854a3a-2127-422b-91ae-364da2661108
Third Party Advisory
https://www.kb.cert.org/vuls/id/434904
Source: af854a3a-2127-422b-91ae-364da2661108

15 reference(s) from NVD

Quick Stats

CVSS v3 Score
5.9 / 10.0
EPSS (Exploit Probability)
23.2%
96th percentile
Exploitation Status
Not in CISA KEV

Weaknesses (CWE)

Affected Vendors

debian fedoraproject thekelleys