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Vulnerability details: VCID-2wu3-v2hz-q3bv
Vulnerability ID VCID-2wu3-v2hz-q3bv
Aliases CVE-2020-12667
Summary Knot Resolver before 5.1.1 allows traffic amplification via a crafted DNS answer from an attacker-controlled server, aka an "NXNSAttack" issue. This is triggered by random subdomains in the NSDNAME in NS records.
Status Published
Exploitability 0.5
Weighted Severity 6.8
Risk 3.4
Affected and Fixed Packages Package Details
Weaknesses (0)
There are no known CWE.
System Score Found at
cvssv3.1 7.5 http://cyber-security-group.cs.tau.ac.il/#
ssvc Track http://cyber-security-group.cs.tau.ac.il/#
epss 0.01022 https://api.first.org/data/v1/epss?cve=CVE-2020-12667
epss 0.01022 https://api.first.org/data/v1/epss?cve=CVE-2020-12667
epss 0.01022 https://api.first.org/data/v1/epss?cve=CVE-2020-12667
epss 0.01022 https://api.first.org/data/v1/epss?cve=CVE-2020-12667
epss 0.01022 https://api.first.org/data/v1/epss?cve=CVE-2020-12667
epss 0.01022 https://api.first.org/data/v1/epss?cve=CVE-2020-12667
epss 0.01022 https://api.first.org/data/v1/epss?cve=CVE-2020-12667
epss 0.01022 https://api.first.org/data/v1/epss?cve=CVE-2020-12667
epss 0.01022 https://api.first.org/data/v1/epss?cve=CVE-2020-12667
epss 0.01022 https://api.first.org/data/v1/epss?cve=CVE-2020-12667
epss 0.01022 https://api.first.org/data/v1/epss?cve=CVE-2020-12667
epss 0.01022 https://api.first.org/data/v1/epss?cve=CVE-2020-12667
epss 0.01022 https://api.first.org/data/v1/epss?cve=CVE-2020-12667
epss 0.01022 https://api.first.org/data/v1/epss?cve=CVE-2020-12667
cvssv3.1 7.5 https://en.blog.nic.cz/2020/05/19/nxnsattack-upgrade-resolvers-to-stop-new-kind-of-random-subdomain-attack/
ssvc Track https://en.blog.nic.cz/2020/05/19/nxnsattack-upgrade-resolvers-to-stop-new-kind-of-random-subdomain-attack/
cvssv3.1 7.5 https://lists.debian.org/debian-lts-announce/2024/04/msg00017.html
ssvc Track https://lists.debian.org/debian-lts-announce/2024/04/msg00017.html
cvssv3.1 7.5 https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/76Y4FITMOH6RVPWAANGV7NB2ZHPJJGDQ/
ssvc Track https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/76Y4FITMOH6RVPWAANGV7NB2ZHPJJGDQ/
cvssv3.1 7.5 https://www.knot-resolver.cz/2020-05-19-knot-resolver-5.1.1.html
ssvc Track https://www.knot-resolver.cz/2020-05-19-knot-resolver-5.1.1.html
cvssv3.1 7.5 http://www.openwall.com/lists/oss-security/2020/05/19/2
ssvc Track http://www.openwall.com/lists/oss-security/2020/05/19/2
Reference id Reference type URL
https://api.first.org/data/v1/epss?cve=CVE-2020-12667
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-12667
# http://cyber-security-group.cs.tau.ac.il/#
2 http://www.openwall.com/lists/oss-security/2020/05/19/2
2020-05-19-knot-resolver-5.1.1.html https://www.knot-resolver.cz/2020-05-19-knot-resolver-5.1.1.html
76Y4FITMOH6RVPWAANGV7NB2ZHPJJGDQ https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/76Y4FITMOH6RVPWAANGV7NB2ZHPJJGDQ/
961076 https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=961076
msg00017.html https://lists.debian.org/debian-lts-announce/2024/04/msg00017.html
nxnsattack-upgrade-resolvers-to-stop-new-kind-of-random-subdomain-attack https://en.blog.nic.cz/2020/05/19/nxnsattack-upgrade-resolvers-to-stop-new-kind-of-random-subdomain-attack/
USN-7047-1 https://usn.ubuntu.com/7047-1/
No exploits are available.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at http://cyber-security-group.cs.tau.ac.il/#
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: SSVCv2/E:N/A:Y/T:P/P:M/B:A/M:M/D:T/2024-04-26T17:02:23Z/ Found at http://cyber-security-group.cs.tau.ac.il/#
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://en.blog.nic.cz/2020/05/19/nxnsattack-upgrade-resolvers-to-stop-new-kind-of-random-subdomain-attack/
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: SSVCv2/E:N/A:Y/T:P/P:M/B:A/M:M/D:T/2024-04-26T17:02:23Z/ Found at https://en.blog.nic.cz/2020/05/19/nxnsattack-upgrade-resolvers-to-stop-new-kind-of-random-subdomain-attack/
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://lists.debian.org/debian-lts-announce/2024/04/msg00017.html
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: SSVCv2/E:N/A:Y/T:P/P:M/B:A/M:M/D:T/2024-04-26T17:02:23Z/ Found at https://lists.debian.org/debian-lts-announce/2024/04/msg00017.html
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/76Y4FITMOH6RVPWAANGV7NB2ZHPJJGDQ/
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: SSVCv2/E:N/A:Y/T:P/P:M/B:A/M:M/D:T/2024-04-26T17:02:23Z/ Found at https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/76Y4FITMOH6RVPWAANGV7NB2ZHPJJGDQ/
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://www.knot-resolver.cz/2020-05-19-knot-resolver-5.1.1.html
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: SSVCv2/E:N/A:Y/T:P/P:M/B:A/M:M/D:T/2024-04-26T17:02:23Z/ Found at https://www.knot-resolver.cz/2020-05-19-knot-resolver-5.1.1.html
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at http://www.openwall.com/lists/oss-security/2020/05/19/2
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: SSVCv2/E:N/A:Y/T:P/P:M/B:A/M:M/D:T/2024-04-26T17:02:23Z/ Found at http://www.openwall.com/lists/oss-security/2020/05/19/2
Exploit Prediction Scoring System (EPSS)
Percentile 0.77187
EPSS Score 0.01022
Published At April 1, 2026, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2026-04-01T16:34:03.416081+00:00 Debian Oval Importer Import https://www.debian.org/security/oval/oval-definitions-bullseye.xml.bz2 38.0.0