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CVE-2020-25687

68
FAUCET Score

CVE-2020-25687 is a heap-based buffer overflow in dnsmasq versions prior to 2.83, affecting various Debian and Fedora distributions. This flaw, dubbed part of "DNSpooq," allows a remote attacker to trigger a denial of service by crafting valid DNS replies when DNSSEC is enabled. With a CVSS score of 5.9 (Medium), it has a network attack vector and high attack complexity, primarily impacting system availability. While there is no known active exploitation or public exploit code, the vulnerability has garnered significant community discussion and media coverage, indicating awareness and potential for future exploitation.

Impacted Technologies

VendorProductVersion(s)CPE
< 2.83CPE matchmatch criteria
cpe:2.3:a:thekelleys:dnsmasq:*:*:*:*:*:*:*:*
32CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*
33CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
9.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
10.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

5.9MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
2.2
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
86.69%
Probability of exploitation in next 30 days
EPSS Percentile
99.7%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.8669 is in the 100th percentile among its peer group of 19,958 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.0 Bluesky, 0.0 Mastodon, and 0.2 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (6)

microsoftpatch availablevia msrc
Product: 19065-16820Fixed in: 2.85-1
microsoftpatch availablevia msrc
Product: cm1 dnsmasq 2.85-1 on CBL Mariner 1.0Fixed in: 2.85-1
redhatpatch availablevia nvd_reference
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: dnsmasq-0:2.79-13.el8_3.1
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8.1 Extended Update SupportFixed in: dnsmasq-0:2.79-6.el8_1.1
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8.2 Extended Update SupportFixed in: dnsmasq-0:2.79-11.el8_2.2
View patch

Vendor Advisories (2)

redhatCVE-2020-25687Moderate

dnsmasq: heap-based buffer overflow with large memcpy in sort_rrset() when DNSSEC is enabled

Jan 19, 2021
microsoft2021-Jan/CVE-2020-25687Moderate

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.

Jan 12, 2021

References

kb.cert.org / vuls/id/434904
bugzilla.redhat.com / show_bug.cgi
Issue TrackingPatchThird Party Advisory
lists.debian.org / debian-lts-announce/2021/03/msg00027.html
Mailing ListThird Party Advisory
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/QGB7HL3OWHTLEPSMLDGOMXQKG3KM2QME
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/WYW3IR6APUSKOYKL5FT3ACTIHWHGQY32
security.gentoo.org / glsa/202101-17
Third Party Advisory
debian.org / security/2021/dsa-4844
Third Party Advisory
jsof-tech.com / disclosures/dnspooq
Third Party Advisory