CVE-2020-8623 | A flaw in native PKCS#11 code can lead to a remotely triggerable assertion failure in pk11.c

In BIND 9.10.0 -> 9.11.21, 9.12.0 -> 9.16.5, 9.17.0 -> 9.17.3, also affects 9.10.5-S1 -> 9.11.21-S1 of the BIND 9 Supported Preview Edition, An attacker that can reach a vulnerable system with a specially crafted query packet can trigger a crash. To be vulnerable, the system must: * be running BIND that was built with "--enable-native-pkcs11" * be signing one or more zones with an RSA key * be able to receive queries from a possible attacker

Published: 2020-08-21 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2020-8623 is rated Moderate Risk (57.5/100): CVSS High severity, with high exploitation likelihood (EPSS 6.35%, 93th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. 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-2020-8623

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 18.32% 6.35% -11.97%
2 2026-03-03 18.12% 18.32% +0.19%
3 2025-12-28 — 18.12% —

Full EPSS history (29 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-8623

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/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:N)
No account or special rights needed—anonymous or random user is enough.
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.
 3.9 3.6 [email protected]
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/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:N)
No account or special rights needed—anonymous or random user is enough.
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.
 3.9 3.6 [email protected]
4.3 2.0 MEDIUM
AV:N/AC:M/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 8.6 2.9 [email protected]

Weakness enumeration for CVE-2020-8623

OS Trackers for CVE-2020-8623

vendor priority summary link
alpine high CVE-2020-8623: 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 10, open 62. https://security.alpinelinux.org/vuln/CVE-2020-8623
debian not yet assigned CVE-2020-8623 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-2020-8623
gentoo normal CVE-2020-8623: 1 GLSA(s) (202008-19), 1 atom(s) (net-dns/bind); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2020-8623
redhat medium — https://access.redhat.com/security/cve/CVE-2020-8623
suse high CVE-2020-8623 severity important: SUSE including 526 source package names (0.1.0:sysuser-shadow-2.0-4.2.8, 0.1.75:sysuser-shadow-2.0-4.2.8, …), 994 product×package rows across 212 product lines (Container bci/bci-init, Container bci/dotnet-aspnet, … (212 product lines)): Fixed 803, Known Affected 157, Known Not Affected 34. https://www.suse.com/security/cve/CVE-2020-8623/
ubuntu medium CVE-2020-8623 medium priority: Ubuntu including 1 source packages (bind9), 5 status rows across 5 suites (bionic, focal, trusty, upstream, xenial): released 3, needs-triage 1, not-affected 1. https://ubuntu.com/security/CVE-2020-8623

Affected software / configurations for CVE-2020-8623

Vendor Product Version Raw CPE
isc bind >= 9.10.0, <= 9.11.21 cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*
isc bind >= 9.12.1, <= 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 9.10.5 cpe:2.3:a:isc:bind:9.10.5: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:*:*:*:*:*:*:*
opensuse leap 15.1 cpe:2.3:o:opensuse:leap:15.1:*:*:*:*:*:*:*
opensuse leap 15.2 cpe:2.3:o:opensuse:leap:15.2:*:*:*:*:*:*:*
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 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:*:*:*
synology dns_server < 2.2.2-5027 cpe:2.3:a:synology:dns_server:*:*:*:*:*:*:*:*
netapp steelstore_cloud_integrated_storage — cpe:2.3:a:netapp:steelstore_cloud_integrated_storage:-:*:*:*:*:*:*:*

References for CVE-2020-8623

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-2020-8623 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://www.debian.org/security/2020/dsa-4752 Third Party Advisory
https://www.synology.com/security/advisory/Synology_SA_20_19 Third Party Advisory
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