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NVD / CVE Program· CNA isc

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

Noroxi assessment

Priority: This week (action score 60/100)

  • A ready-made attack module is public (Metasploit); exploiting it takes no special expertise.
  • A ready-made attack tool exists and the flaw can be exploited over the network without an account, so priority is at least “This week”.
  • Probability of exploitation in the next 30 days: 93.3% (FIRST EPSS); higher than 99.8% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. Special conditions such as timing or configuration are required.
  • Fixed version: bind (Alpine:v3.10) 9.14.12-r0; bind9 (Debian:10) 1:9.11.5.P4+dfsg-5.1+deb10u1; bind9 (Debian:12) 1:9.16.3-1.
  • Mentioned 5 times in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Don’t wait for the next maintenance window. Upgrade to bind (Alpine:v3.10) 9.14.12-r0; bind9 (Debian:10) 1:9.11.5.P4+dfsg-5.1+deb10u1; bind9 (Debian:12) 1:9.16.3-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

MediumCVSS 5.9 · v3.1—Weaponized Fix available
Published
May 19, 2020
Updated
Jun 16, 2026
EPSS
93.3% · 99th percentile

Report tools

JSON

Action score

60

This week

Don’t wait for the next maintenance window.

CVSS
23 / 40 · 5.9 / 10
CISA KEV
0 / 30 · Not listed
EPSS
28 / 30 · 93.3%
Ready-made attack tool
9 / 60 · floor: at least 60

CNA vs NVD score

NVD
5.9
CNA · isc
7.5
1.6 point gap

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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  • Not in KEV: no record of exploitation in the wild
  • Weaponized exploit exists
  • A fix has been released

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  • when exploit code appears or is weaponized
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  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
iscbind
debiandebian linux
fedoraprojectfedora
opensuseleap
canonicalubuntu linux

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • canonical ubuntu linux12.04
  • canonical ubuntu linux14.04
  • canonical ubuntu linux16.04
  • canonical ubuntu linux18.04
  • canonical ubuntu linux19.10
  • canonical ubuntu linux20.04
  • debian debian linux10.0
  • debian debian linux8.0
  • debian debian linux9.0
  • fedoraproject fedora31
  • fedoraproject fedora32
  • isc bind9.0.0 and later · up to 9.11.18 inclusive
  • isc bind9.12.0 and later · up to 9.12.4 inclusive
  • isc bind9.13.0 and later · up to 9.13.7 inclusive
  • isc bind9.14.0 and later · up to 9.14.11 inclusive
  • isc bind9.15.0 and later · up to 9.15.6 inclusive
  • isc bind9.16.0 and later · up to 9.16.2 inclusive
  • isc bind9.17.0 and later · up to 9.17.1 inclusive
  • isc bind9.10.5
  • isc bind9.10.7

Versions reported by the vendor

Affected version ranges reported by the assigning authority (isc). Independent of NVD's CPE analysis and usually ahead of it.

  • ISC BIND9

    • 9.0.0 -> 9.11.18, 9.12.0 -> 9.12.4-P2, 9.14.0 -> 9.14.11, 9.16.0 -> 9.16.2, and releases 9.17.0 -> 9.17.1 of the 9.17 experimental development branch. All releases in the obsolete 9.13 and 9.15 develoaffected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Alpine:v3.10bindfrom 9.0.0 · before 9.14.12-r09.14.12-r0
Debian:10bind9before 1:9.11.5.P4+dfsg-5.1+deb10u11:9.11.5.P4+dfsg-5.1+deb10u1
Debian:12bind9before 1:9.16.3-11:9.16.3-1
Debian:8bind9before 1:9.9.5.dfsg-9+deb8u191:9.9.5.dfsg-9+deb8u19
Debian:9bind9before 1:9.10.3.dfsg.P4-12.3+deb9u61:9.10.3.dfsg.P4-12.3+deb9u6
openSUSE:Leap 15.1bindbefore 9.16.6-lp151.11.9.19.16.6-lp151.11.9.1
openSUSE:Leap 15.1libuvbefore 1.18.0-lp151.3.3.11.18.0-lp151.3.3.1
openSUSE:Leap 15.1sysuser-toolsbefore 2.0-lp151.4.3.12.0-lp151.4.3.1
openSUSE:Leap 15.2bindbefore 9.16.6-lp152.14.3.19.16.6-lp152.14.3.1
openSUSE:Leap 15.2libuvbefore 1.18.0-lp152.4.3.11.18.0-lp152.4.3.1
openSUSE:Leap 15.2sysuser-toolsbefore 2.0-lp152.5.3.12.0-lp152.5.3.1
openSUSE:Tumbleweedbindbefore 9.16.20-1.49.16.20-1.4
Red Hat:enterprise_linux:6::clientbindbefore 32:9.8.2-0.68.rc1.el6_10.732:9.8.2-0.68.rc1.el6_10.7
Red Hat:enterprise_linux:6::clientbind-chrootbefore 32:9.8.2-0.68.rc1.el6_10.732:9.8.2-0.68.rc1.el6_10.7
Red Hat:enterprise_linux:6::clientbind-debuginfobefore 32:9.8.2-0.68.rc1.el6_10.732:9.8.2-0.68.rc1.el6_10.7
Red Hat:enterprise_linux:6::clientbind-develbefore 32:9.8.2-0.68.rc1.el6_10.732:9.8.2-0.68.rc1.el6_10.7
Red Hat:enterprise_linux:6::clientbind-libsbefore 32:9.8.2-0.68.rc1.el6_10.732:9.8.2-0.68.rc1.el6_10.7
Red Hat:enterprise_linux:6::clientbind-sdbbefore 32:9.8.2-0.68.rc1.el6_10.732:9.8.2-0.68.rc1.el6_10.7
Red Hat:enterprise_linux:6::clientbind-utilsbefore 32:9.8.2-0.68.rc1.el6_10.732:9.8.2-0.68.rc1.el6_10.7
Red Hat:enterprise_linux:7::clientbindbefore 32:9.11.4-16.P2.el7_8.632:9.11.4-16.P2.el7_8.6
Red Hat:enterprise_linux:7::clientbind-chrootbefore 32:9.11.4-16.P2.el7_8.632:9.11.4-16.P2.el7_8.6
Red Hat:enterprise_linux:7::clientbind-debuginfobefore 32:9.11.4-16.P2.el7_8.632:9.11.4-16.P2.el7_8.6
Red Hat:enterprise_linux:7::clientbind-develbefore 32:9.11.4-16.P2.el7_8.632:9.11.4-16.P2.el7_8.6
Red Hat:enterprise_linux:7::clientbind-export-develbefore 32:9.11.4-16.P2.el7_8.632:9.11.4-16.P2.el7_8.6

+96

Same product

isc: all records

Other highest-scoring records for the same primary product.

  • CVE-2015-5477named in ISC BIND 9.x before 9.9.7-P2 and 9.10.x before 9.10.2-P3 allows remote attackers to cause a denial of service (REQUIRE assertion faKEV
    90Now
  • CVE-2016-2776buffer.c in named in ISC BIND 9 before 9.9.9-P3, 9.10.x before 9.10.4-P3, and 9.11.x before 9.11.0rc3 does not properly construct responses,
    60This week
  • CVE-2016-1286named in ISC BIND 9.x before 9.9.8-P4 and 9.10.x before 9.10.3-P4 allows remote attackers to cause a denial of service (assertion failure an
    52Plan

Published before and after this one in the same product

  • ← EarlierCVE-2019-6477Nov 26, 2019 · TCP-pipelined queries can bypass tcp-clients limit
    31Monitor
  • ← EarlierCVE-2020-8616May 19, 2020 · BIND does not sufficiently limit the number of fetches performed when processing referrals
    37Monitor
  • Later →CVE-2020-8618Jun 17, 2020 · A buffer boundary check assertion in rdataset.c can fail incorrectly during zone transfer
    20Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
alpine:bind9.14.12-r0 · Alpine:v3.10Package registry (OSV)
debian:bind91:9.16.3-1 · Debian:12Package registry (OSV)
opensuse:bind9.16.6-lp152.14.3.1 · openSUSE:Leap 15.2Package registry (OSV)
opensuse:libuv1.18.0-lp152.4.3.1 · openSUSE:Leap 15.2Package registry (OSV)
opensuse:sysuser-tools2.0-lp152.5.3.1 · openSUSE:Leap 15.2Package registry (OSV)
red hat:bind32:9.11.13-5.el8_2 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:bind-chroot32:9.11.13-5.el8_2 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:bind-debuginfo32:9.11.13-5.el8_2 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:bind-debugsource32:9.11.13-5.el8_2 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:bind-devel32:9.11.13-5.el8_2 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:bind-export-libs-debuginfo32:9.11.13-5.el8_2 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:bind-libs32:9.11.13-5.el8_2 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:bind-libs-debuginfo32:9.11.13-5.el8_2 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:bind-libs-lite32:9.11.13-5.el8_2 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:bind-libs-lite-debuginfo32:9.11.13-5.el8_2 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:bind-license32:9.11.13-5.el8_2 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:bind-lite-devel32:9.11.13-5.el8_2 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
suse:bind9.11.2-3.17.1 · SUSE:Linux Enterprise Software Development Kit 12 SP4Package registry (OSV)
suse:sysuser-tools2.0-4.2.8 · SUSE:Linux Enterprise Module for Basesystem 15 SP1Package registry (OSV)

Exploit status

Weaponized

A ready exploit tool or active in-the-wild use is known for this vulnerability. This should be your top priority.

Evidence

  • Metasploit module ×1
  • Exploit-DB entry ×1
  • Proof-of-concept repository on GitHub ×2

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Metasploit moduleauxiliary/dos/dns/bind_tsig_badtimeBIND TSIG Badtime Query Denial of Serviceauxiliary2020-05-19
Proof-of-concept repository on GitHubstars:452020-05-20
Proof-of-concept repository on GitHubstars:02020-05-26
Exploit-DB entrydos2020-05-20

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. Metasploitsame day
  2. Published
  3. First PoC+1 d
  4. TodayNov 5, 2026+2361 d

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • Special conditions such as timing or configuration are required.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-617 · Reachable Assertion

CVSS vector

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

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (11 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records