CVE-2020-8622 | A truncated TSIG response can lead to an assertion failure

In BIND 9.0.0 -> 9.11.21, 9.12.0 -> 9.16.5, 9.17.0 -> 9.17.3, also affects 9.9.3-S1 -> 9.11.21-S1 of the BIND 9 Supported Preview Edition, An attacker on the network path for a TSIG-signed request, or operating the server receiving the TSIG-signed request, could send a truncated response to that request, triggering an assertion failure, causing the server to exit. Alternately, an off-path attacker would have to correctly guess when a TSIG-signed request was sent, along with other characteristics of the packet and message, and spoof a truncated response to trigger an assertion failure, causing the server to exit.

Published: 2020-08-21 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2020-8622 is rated Moderate Risk (61/100): CVSS Medium severity, with high exploitation likelihood (EPSS 5.54%, 92th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. EPSS rose +2.92% over the last day, indicating growing attacker interest. High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2020-8622

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 2.63% 5.54% +2.92%
2 2026-03-03 2.40% 2.63% +0.23%
3 2026-01-31 — 2.40% —

Full EPSS history (22 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-8622

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.8 3.6 [email protected]
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.8 3.6 [email protected]
4.0 2.0 MEDIUM
AV:N/AC:L/Au:S/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:S)
A single authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 8.0 2.9 [email protected]

Weakness enumeration for CVE-2020-8622

OS Trackers for CVE-2020-8622

vendor priority summary link
alpine medium CVE-2020-8622: 1 source package rows (bind); 72 state rows across 10 repos (3.10-main, 3.11-main, 3.12-main, 3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 12, open 60. https://security.alpinelinux.org/vuln/CVE-2020-8622
debian not yet assigned CVE-2020-8622 not yet assigned priority: Debian including 1 source packages (bind9), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2020-8622
gentoo normal CVE-2020-8622: 1 GLSA(s) (202008-19), 1 atom(s) (net-dns/bind); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2020-8622
redhat medium — https://access.redhat.com/security/cve/CVE-2020-8622
suse high CVE-2020-8622 severity important: SUSE including 532 source package names (0.1.0:sysuser-shadow-2.0-4.2.8, 0.1.75:sysuser-shadow-2.0-4.2.8, …), 1048 product×package rows across 221 product lines (Container bci/bci-init, Container bci/dotnet-aspnet, … (221 product lines)): Fixed 857, Known Affected 157, Known Not Affected 34. https://www.suse.com/security/cve/CVE-2020-8622/
ubuntu medium CVE-2020-8622 medium priority: Ubuntu including 1 source packages (bind9), 5 status rows across 5 suites (bionic, focal, trusty, upstream, xenial): released 4, needs-triage 1. https://ubuntu.com/security/CVE-2020-8622

Affected software / configurations for CVE-2020-8622

Vendor Product Version Raw CPE
isc bind >= 9.0.0, <= 9.11.21 cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*
isc bind >= 9.12.0, <= 9.16.5 cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*
isc bind >= 9.17.0, <= 9.17.3 cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*
isc bind 9.9.3 cpe:2.3:a:isc:bind:9.9.3:s1:*:*:supported_preview:*:*:*
isc bind 9.11.21 cpe:2.3:a:isc:bind:9.11.21:s1:*:*:supported_preview:*:*:*
fedoraproject fedora 31 cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:*
fedoraproject fedora 32 cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*
debian debian_linux 9.0 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
debian debian_linux 10.0 cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
canonical ubuntu_linux 12.04 cpe:2.3:o:canonical:ubuntu_linux:12.04:*:*:*:-:*:*:*
canonical ubuntu_linux 14.04 cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:esm:*:*:*
canonical ubuntu_linux 16.04 cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:esm:*:*:*
canonical ubuntu_linux 18.04 cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
canonical ubuntu_linux 20.04 cpe:2.3:o:canonical:ubuntu_linux:20.04:*:*:*:lts:*:*:*
netapp steelstore_cloud_integrated_storage — cpe:2.3:a:netapp:steelstore_cloud_integrated_storage:-:*:*:*:*:*:*:*
opensuse leap 15.1 cpe:2.3:o:opensuse:leap:15.1:*:*:*:*:*:*:*
opensuse leap 15.2 cpe:2.3:o:opensuse:leap:15.2:*:*:*:*:*:*:*
synology dns_server < 2.2.2-5028 cpe:2.3:a:synology:dns_server:*:*:*:*:*:*:*:*
oracle communications_diameter_signaling_router >= 8.0.0, <= 8.5.0 cpe:2.3:a:oracle:communications_diameter_signaling_router:*:*:*:*:*:*:*:*

References for CVE-2020-8622

URL Tags
http://lists.opensuse.org/opensuse-security-announce/2020-10/msg00041.html Mailing List Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-10/msg00044.html Mailing List Third Party Advisory
https://kb.isc.org/docs/cve-2020-8622 Vendor Advisory
https://lists.debian.org/debian-lts-announce/2020/08/msg00053.html Mailing List Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/DQN62GBMCIC5AY4KYADGXNKVY6AJKSJE/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZKAMJZXR66P6S5LEU4SN7USSNCWTXEXP/
https://security.gentoo.org/glsa/202008-19 Third Party Advisory
https://security.netapp.com/advisory/ntap-20200827-0003/ Third Party Advisory
https://usn.ubuntu.com/4468-1/ Third Party Advisory
https://usn.ubuntu.com/4468-2/ Third Party Advisory
https://www.debian.org/security/2020/dsa-4752 Third Party Advisory
https://www.oracle.com/security-alerts/cpuoct2021.html Patch Third Party Advisory
https://www.synology.com/security/advisory/Synology_SA_20_19 Third Party Advisory
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