CVE-2020-8617 | A logic error in code which checks TSIG validity can be used to trigger an assertion failure in tsig.c

Exp

Using a specially-crafted message, an attacker may potentially cause a BIND server to reach an inconsistent state if the attacker knows (or successfully guesses) the name of a TSIG key used by the server. Since BIND, by default, configures a local session key even on servers whose configuration does not otherwise make use of it, almost all current BIND servers are vulnerable. In releases of BIND dating from March 2018 and after, an assertion check in tsig.c detects this inconsistent state and deliberately exits. Prior to the introduction of the check the server would continue operating in an inconsistent state, with potentially harmful results.

Published: 2020-05-19 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2020-8617 is rated High Exploit Risk (82.8/100): CVSS High severity, with high exploitation likelihood (EPSS 92.63%, 100th percentile). 1 public exploit reference(s) are indexed (Exploit-DB). EPSS rose +2.89% over the last day, indicating growing attacker interest. Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

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

Public exploit references (Exploit-DB) for CVE-2020-8617

EDB-ID Source Kind Published Link
48521 exploit_db edb 2020-05-20 Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2020-8617

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 2026-04-09 89.74% 92.63% +2.89%
2 2026-04-07 89.83% 89.74% -0.09%
3 2026-03-25 — 89.83% —

Full EPSS history (40 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-8617

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]
5.9 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/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:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
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.
 2.2 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-2020-8617

OS Trackers for CVE-2020-8617

vendor priority summary link
alpine high CVE-2020-8617: 1 source package rows (bind); 60 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 50. https://security.alpinelinux.org/vuln/CVE-2020-8617
debian not yet assigned CVE-2020-8617 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-2020-8617
redhat high — https://access.redhat.com/security/cve/CVE-2020-8617
suse high CVE-2020-8617 severity important: SUSE including 529 source package names (0.1.0:sysuser-shadow-2.0-4.2.8, 0.1.75:sysuser-shadow-2.0-4.2.8, …), 896 product×package rows across 222 product lines (Container bci/bci-init, Container bci/dotnet-aspnet, … (222 product lines)): Fixed 739, Known Affected 157. https://www.suse.com/security/cve/CVE-2020-8617/
ubuntu medium CVE-2020-8617 medium priority: Ubuntu including 1 source packages (bind9), 6 status rows across 6 suites (bionic, eoan, focal, trusty, upstream, xenial): released 5, needs-triage 1. https://ubuntu.com/security/CVE-2020-8617

Affected software / configurations for CVE-2020-8617

Vendor Product Version Raw CPE
isc bind >= 9.0.0, <= 9.11.18 cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*
isc bind >= 9.12.0, <= 9.12.4 cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*
isc bind >= 9.13.0, <= 9.13.7 cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*
isc bind >= 9.14.0, <= 9.14.11 cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*
isc bind >= 9.15.0, <= 9.15.6 cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*
isc bind >= 9.16.0, <= 9.16.2 cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*
isc bind >= 9.17.0, <= 9.17.1 cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*
isc bind 9.12.4 cpe:2.3:a:isc:bind:9.12.4:p1:*:*:*:*:*:*
isc bind 9.12.4 cpe:2.3:a:isc:bind:9.12.4:p2:*:*:*:*:*:*
isc bind 9.9.3 cpe:2.3:a:isc:bind:9.9.3:s1:*:*:supported_preview:*:*:*
isc bind 9.10.5 cpe:2.3:a:isc:bind:9.10.5:s1:*:*:supported_preview:*:*:*
isc bind 9.10.7 cpe:2.3:a:isc:bind:9.10.7:s1:*:*:supported_preview:*:*:*
isc bind 9.11.3 cpe:2.3:a:isc:bind:9.11.3:s1:*:*:supported_preview:*:*:*
isc bind 9.11.5 cpe:2.3:a:isc:bind:9.11.5:s3:*:*:supported_preview:*:*:*
isc bind 9.11.5 cpe:2.3:a:isc:bind:9.11.5:s5:*:*:supported_preview:*:*:*
isc bind 9.11.6 cpe:2.3:a:isc:bind:9.11.6:s1:*:*:supported_preview:*:*:*
isc bind 9.11.7 cpe:2.3:a:isc:bind:9.11.7:s1:*:*:supported_preview:*:*:*
isc bind 9.11.8 cpe:2.3:a:isc:bind:9.11.8:s1:*:*:supported_preview:*:*:*
debian debian_linux 8.0 cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
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:*:*:*:*:*:*:*
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:*:*:*:*:*:*:*
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 19.10 cpe:2.3:o:canonical:ubuntu_linux:19.10:*:*:*:*:*:*:*
canonical ubuntu_linux 20.04 cpe:2.3:o:canonical:ubuntu_linux:20.04:*:*:*:lts:*:*:*

References for CVE-2020-8617

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
http://packetstormsecurity.com/files/157836/BIND-TSIG-Denial-Of-Service.html Third Party Advisory VDB Entry
http://www.openwall.com/lists/oss-security/2020/05/19/4 Mailing List Patch Third Party Advisory
https://kb.isc.org/docs/cve-2020-8617 Patch Vendor Advisory
https://lists.debian.org/debian-lts-announce/2020/05/msg00031.html Mailing List Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JKJXVBOKZ36ER3EUCR7VRB7WGHIIMPNJ/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WOGCJS2XQ3SQNF4W6GLZ73LWZJ6ZZWZI/
https://security.netapp.com/advisory/ntap-20200522-0002/ Third Party Advisory
https://usn.ubuntu.com/4365-1/ Third Party Advisory
https://usn.ubuntu.com/4365-2/ Third Party Advisory
https://www.debian.org/security/2020/dsa-4689 Third Party Advisory
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