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CVE-2020-12667

20
FAUCET Score

CVE-2020-12667 describes an NXNSAttack vulnerability in Knot Resolver versions prior to 5.1.1, allowing for DNS traffic amplification. This high-severity vulnerability (CVSS 7.5) has a low attack complexity and can lead to denial-of-service (DoS) attacks by leveraging crafted DNS answers from attacker-controlled servers. While there is no known active exploitation or public exploit code (Metasploit, Nuclei, ExploitDB), the vulnerability has garnered significant community discussion and media coverage, indicating awareness of its potential impact.

Impacted Technologies

VendorProductVersion(s)CPE
< 5.1.1CPE matchmatch criteria
cpe:2.3:a:nic:knot_resolver:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
2.62%
Probability of exploitation in next 30 days
EPSS Percentile
83.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0262 is in the 71st percentile among its peer group of 51,506 CVEs.

Social Chatter

No social media mentions found for this CVE.

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

cyber-security-group.cs.tau.ac.il
Technical DescriptionThird Party Advisory
en.blog.nic.cz / 2020/05/19/nxnsattack-upgrade-resolvers-to-stop-new-kind-of-random-subdomain-attack
Technical DescriptionVendor Advisory
lists.debian.org / debian-lts-announce/2024/04/msg00017.html
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/76Y4FITMOH6RVPWAANGV7NB2ZHPJJGDQ
knot-resolver.cz / 2020-05-19-knot-resolver-5.1.1.html
Release NotesVendor Advisory
openwall.com / lists/oss-security/2020/05/19/2
Mailing ListThird Party Advisory