Skip to content
Noroxi
CVE-2020-8622· NVD / CVE Program· CNA isc

A truncated TSIG response can lead to an assertion failure

Noroxi assessment

Priority: Monitor (action score 28/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 5.7% (FIRST EPSS); higher than 93% of all records.
  • Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: ISC BIND9 9.11.22-S1.
  • Mentioned 6 times in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to ISC BIND9 9.11.22-S1 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

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.

MediumCVSS 6.5 · v3.1—No exploit Fix available
Published
Aug 21, 2020
Updated
Jun 16, 2026
EPSS
5.7% · 93th percentile

Report tools

JSON

Action score

28

Monitor

Low priority for now.

CVSS
26 / 40 · 6.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
2 / 30 · 5.7%

CNA vs NVD score

NVD
6.5
CNA · isc
6.5
agree

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

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2020-8622

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

One daily email digest (06:00 UTC); connect a webhook for KEV listings and weaponized exploits instantly.

Your free account also gets you

Running WordPress? Scan your site free with WP Lens

  • Stack alerts: add the products and versions you run, get the new CVEs that affect them
  • Uptime monitoring: 1 site, instant email when it goes down
  • Add your domain: subdomains and takeover risk scanned every week (1 domain)
  • 10 scans an hour on the security tools (3 a day without an account), an API key and MCP
  • All your scans in one panel: findings, what changed in the last scan, a report per domain or per client (PDF, share link)
All free tools

Sign up with email · Have an account? Sign in

Free account, no card. Unfollow any time.

Don't want an account? Get "Exploited this week" by email every MondayDon't want an account? RSS feed for isc records

Running WordPress? Scan your site free with WP Lens

Is your version affected? Check it

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.

We use this product, ask for help

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
fedoraprojectfedora
debiandebian linux
canonicalubuntu linux
netappsteelstore cloud integrated storage
opensuseleap
synologydns server
oraclecommunications diameter signaling router

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 linux20.04
  • debian debian linux10.0
  • debian debian linux9.0
  • fedoraproject fedora31
  • fedoraproject fedora32
  • isc bind9.0.0 and later · up to 9.11.21 inclusive
  • isc bind9.12.0 and later · up to 9.16.5 inclusive
  • isc bind9.17.0 and later · up to 9.17.3 inclusive
  • isc bind9.11.21
  • isc bind9.9.3
  • netapp steelstore cloud integrated storageall versions
  • opensuse leap15.1
  • opensuse leap15.2
  • oracle communications diameter signaling router8.0.0 and later · up to 8.5.0 inclusive
  • synology dns serverbefore 2.2.2-5028

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 and later · before unspecifiedaffected
    • unspecified and later · before 9.11.22affected
    • 9.12.0 and later · before unspecifiedaffected
    • unspecified and later · before 9.16.6affected
    • 9.17.0 and later · before unspecifiedaffected
    • unspecified and later · before 9.17.4affected
    • 9.9.3-S1 and later · before Supported Preview*affectedfixed in 9.11.22-S1

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 9.16.6-r09.16.6-r0
Debian:10bind9before 1:9.11.5.P4+dfsg-5.1+deb10u21:9.11.5.P4+dfsg-5.1+deb10u2
Debian:12bind9before 1:9.16.6-11:9.16.6-1
Debian:9bind9before 1:9.10.3.dfsg.P4-12.3+deb9u71:9.10.3.dfsg.P4-12.3+deb9u7
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
Red Hat:enterprise_linux:6::clientbindbefore 32:9.8.2-0.68.rc1.el6_10.832:9.8.2-0.68.rc1.el6_10.8
Red Hat:enterprise_linux:6::clientbind-chrootbefore 32:9.8.2-0.68.rc1.el6_10.832:9.8.2-0.68.rc1.el6_10.8
Red Hat:enterprise_linux:6::clientbind-debuginfobefore 32:9.8.2-0.68.rc1.el6_10.832:9.8.2-0.68.rc1.el6_10.8
Red Hat:enterprise_linux:6::clientbind-develbefore 32:9.8.2-0.68.rc1.el6_10.832:9.8.2-0.68.rc1.el6_10.8
Red Hat:enterprise_linux:6::clientbind-libsbefore 32:9.8.2-0.68.rc1.el6_10.832:9.8.2-0.68.rc1.el6_10.8
Red Hat:enterprise_linux:6::clientbind-sdbbefore 32:9.8.2-0.68.rc1.el6_10.832:9.8.2-0.68.rc1.el6_10.8
Red Hat:enterprise_linux:6::clientbind-utilsbefore 32:9.8.2-0.68.rc1.el6_10.832:9.8.2-0.68.rc1.el6_10.8
Red Hat:enterprise_linux:7::clientbindbefore 32:9.11.4-26.P2.el7_9.232:9.11.4-26.P2.el7_9.2
Red Hat:enterprise_linux:7::clientbind-chrootbefore 32:9.11.4-26.P2.el7_9.232:9.11.4-26.P2.el7_9.2
Red Hat:enterprise_linux:7::clientbind-debuginfobefore 32:9.11.4-26.P2.el7_9.232:9.11.4-26.P2.el7_9.2
Red Hat:enterprise_linux:7::clientbind-develbefore 32:9.11.4-26.P2.el7_9.232:9.11.4-26.P2.el7_9.2
Red Hat:enterprise_linux:7::clientbind-export-develbefore 32:9.11.4-26.P2.el7_9.232:9.11.4-26.P2.el7_9.2
Red Hat:enterprise_linux:7::clientbind-export-libsbefore 32:9.11.4-26.P2.el7_9.232:9.11.4-26.P2.el7_9.2
Red Hat:enterprise_linux:7::clientbind-libsbefore 32:9.11.4-26.P2.el7_9.232:9.11.4-26.P2.el7_9.2

+73

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-2020-8617A logic error in code which checks TSIG validity can be used to trigger an assertion failure in tsig.c
    60This week
  • 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

Published before and after this one in the same product

  • ← EarlierCVE-2020-8620Aug 21, 2020 · In BIND 9.15.6 -> 9.16.5, 9.17.0 -> 9.17.3, An attacker who can establish a TCP connection with the server and send data on that connection
    31Monitor
  • ← EarlierCVE-2020-8621Aug 21, 2020 · Attempting QNAME minimization after forwarding can lead to an assertion failure in resolver.c
    31Monitor
  • Later →CVE-2020-8623Aug 21, 2020 · A flaw in native PKCS#11 code can lead to a remotely triggerable assertion failure in pk11.c
    32Monitor

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
ISC BIND99.11.22-S1Vendor (CNA)
alpine:bind9.16.6-r0 · Alpine:v3.10Package registry (OSV)
debian:bind91:9.16.6-1 · 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:bind32:9.8.2-0.68.rc1.el6_10.8 · Red Hat:enterprise_linux:6::clientPackage registry (OSV)
red hat:bind-chroot32:9.8.2-0.68.rc1.el6_10.8 · Red Hat:enterprise_linux:6::clientPackage registry (OSV)
red hat:bind-debuginfo32:9.8.2-0.68.rc1.el6_10.8 · Red Hat:enterprise_linux:6::clientPackage registry (OSV)
red hat:bind-debugsource32:9.11.20-5.el8 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:bind-devel32:9.8.2-0.68.rc1.el6_10.8 · Red Hat:enterprise_linux:6::clientPackage registry (OSV)
red hat:bind-export-libs-debuginfo32:9.11.20-5.el8 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:bind-libs32:9.8.2-0.68.rc1.el6_10.8 · Red Hat:enterprise_linux:6::clientPackage registry (OSV)
red hat:bind-libs-debuginfo32:9.11.20-5.el8 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:bind-libs-lite32:9.11.20-5.el8 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:bind-libs-lite-debuginfo32:9.11.20-5.el8 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:bind-sdb32:9.8.2-0.68.rc1.el6_10.8 · Red Hat:enterprise_linux:6::clientPackage registry (OSV)
red hat:bind-utils32:9.8.2-0.68.rc1.el6_10.8 · Red Hat:enterprise_linux:6::clientPackage registry (OSV)
suse:bind9.11.22-3.22.1 · SUSE:OpenStack Cloud 9Package registry (OSV)
suse:sysuser-tools2.0-4.2.8 · SUSE:Linux Enterprise Module for Basesystem 15 SP1Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

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.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

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.

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.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
Low
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:L/PR:L/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 (12 more)

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

All records