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CVE-2020-8616

33
FAUCET Score

CVE-2020-8616, also known as NXNSAttack, is a critical vulnerability affecting ISC BIND and Debian BIND DNS servers. It allows an attacker to craft malicious DNS referrals, causing a recursing server to issue an excessive number of fetches. This can lead to denial-of-service (DoS) due to degraded server performance and enables high-amplification reflection attacks. With a CVSS score of 8.6 (High), the vulnerability is easily exploitable over the network without user interaction, posing a significant risk for resource exhaustion. While there is no public exploit code available (Metasploit, Nuclei, ExploitDB), the vulnerability has garnered substantial community attention and media coverage, indicating its potential for future exploitation.

Impacted Technologies

VendorProductVersion(s)CPE
>= 9.0.0, <= 9.11.18CPE matchmatch criteria
cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*
>= 9.12.0, <= 9.12.4CPE matchmatch criteria
cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*
>= 9.13.0, <= 9.13.7CPE matchmatch criteria
cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*
>= 9.14.0, <= 9.14.11CPE matchmatch criteria
cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*
>= 9.15.0, <= 9.15.6CPE matchmatch criteria
cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.6HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
4.0
CvssVersion
3.1

Exploit Intelligence

EPSS Score
10.59%
Probability of exploitation in next 30 days
EPSS Percentile
95.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.1059 is in the 93rd percentile among its peer group of 51,553 CVEs.

Social Chatter

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

Patch Available

Vendor Patches (16)

redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: bind-32:9.8.2-0.68.rc1.el6_10.7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 6.5 Advanced Update SupportFixed in: bind-32:9.8.2-0.23.rc1.el6_5.9
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 6.6 Advanced Update SupportFixed in: bind-32:9.8.2-0.30.rc1.el6_6.11
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: bind-32:9.11.4-16.P2.el7_8.6
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7.2 Advanced Update SupportFixed in: bind-32:9.9.4-29.el7_2.9
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7.3 Advanced Update SupportFixed in: bind-32:9.9.4-50.el7_3.4
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7.3 Telco Extended Update SupportFixed in: bind-32:9.9.4-50.el7_3.4
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7.3 Update Services for SAP SolutionsFixed in: bind-32:9.9.4-50.el7_3.4
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7.4 Advanced Update SupportFixed in: bind-32:9.9.4-51.el7_4.4
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7.4 Telco Extended Update SupportFixed in: bind-32:9.9.4-51.el7_4.4
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7.4 Update Services for SAP SolutionsFixed in: bind-32:9.9.4-51.el7_4.4
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7.6 Extended Update SupportFixed in: bind-32:9.9.4-74.el7_6.4
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7.7 Extended Update SupportFixed in: bind-32:9.11.4-9.P2.el7_7.2
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: bind-32:9.11.13-5.el8_2
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8.0 Update Services for SAP SolutionsFixed in: bind-32:9.11.4-19.P2.el8_0
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8.1 Extended Update SupportFixed in: bind-32:9.11.4-26.P2.el8_1.3
View patch

Vendor Advisories (1)

redhatCVE-2020-8616Important

bind: BIND does not sufficiently limit the number of fetches performed when processing referrals

May 19, 2020

References

lists.opensuse.org / opensuse-security-announce/2020-10/msg00041.html
lists.opensuse.org / opensuse-security-announce/2020-10/msg00044.html
kb.isc.org / docs/cve-2020-8616
PatchVendor Advisory
lists.debian.org / debian-lts-announce/2020/05/msg00031.html
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/JKJXVBOKZ36ER3EUCR7VRB7WGHIIMPNJ
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/WOGCJS2XQ3SQNF4W6GLZ73LWZJ6ZZWZI
security.netapp.com / advisory/ntap-20200522-0002
usn.ubuntu.com / 4365-1
usn.ubuntu.com / 4365-2
debian.org / security/2020/dsa-4689
Third Party Advisory
synology.com / security/advisory/Synology_SA_20_12
nxnsattack.com
ExploitThird Party Advisory
openwall.com / lists/oss-security/2020/05/19/4
Mailing ListPatchThird Party Advisory