CVE-2020-3923: DVR firmware in TAT-76 and TAT-77 series of products, provided by TONNET, contain misconfigured authentication

Q: How do I fix CVE-2020-3923?

tat-77104g1 firmware: upgrade to newer than tat-77104g1_20190107; tat-70432n firmware: upgrade to newer than tat-77208g1_20181225; tat-71416g1 firmware: upgrade to newer than tat-71416g1_20181225. Exact commands for each OS are on this page.

Q: Is CVE-2020-3923 being exploited?

CVE-2020-3923 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2020-3923 affect?

CVE-2020-3923 affects tat-77104g1 firmware, tat-70432n firmware, tat-71416g1 firmware. Severity is high (CVSS 8.1). DVR firmware in TAT-76 and TAT-77 series of products, provided by TONNET, contain misconfigured authentication mechanism. Attackers can crack the default password and gain access to the system.

Q: How urgent is CVE-2020-3923?

Priority 53/100. High severity; Remotely exploitable, no login, no user action

This month

HIGH 8.1REMOTEUPGRADEUPGRADEUPGRADE

CVE-2020-3923 is a high-severity flaw (CVSS 8.1) affecting tat-77104g1 firmware, tat-70432n firmware, tat-71416g1 firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

DVR firmware in TAT-76 and TAT-77 series of products, provided by TONNET, contain misconfigured authentication mechanism. Attackers can crack the default password and gain access to the system.

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	8.1 (High)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	1.7% (top 23%)
CISA exploited list	No
Weakness	CWE-287
Published	2020-02-27
Last modified	2026-06-17

Publisher (CNA): TWCERT/CC · Vendor: tonnet

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2020-02-27 04:15 UTCPublished CVE record published
2026-06-17 03:19 UTCUpdated Record last modified

tonnet tat-77104g1 firmware UPGRADE

Affected: <= tat-77104g1_20190107

Fixed in: newer than tat-77104g1_20190107

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

tonnet tat-70432n firmware UPGRADE

Affected: <= tat-77208g1_20181225

Fixed in: newer than tat-77208g1_20181225

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

tonnet tat-71416g1 firmware UPGRADE

Affected: <= tat-71416g1_20181225

Fixed in: newer than tat-71416g1_20181225

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

tonnet tat-71832g1 firmware UPGRADE

Affected: <= tat-71832g1_20190510

Fixed in: newer than tat-71832g1_20190510

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

tonnet tat-76104g3 firmware UPGRADE

Affected: <= 20181220_76104g3

Fixed in: newer than 20181220_76104g3

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

tonnet tat-76108g3 firmware UPGRADE

Affected: <= 20181221_76208g3

Fixed in: newer than 20181221_76208g3

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2020-3923?

tat-77104g1 firmware: upgrade to newer than tat-77104g1_20190107; tat-70432n firmware: upgrade to newer than tat-77208g1_20181225; tat-71416g1 firmware: upgrade to newer than tat-71416g1_20181225. Exact commands for each OS are on this page.

Is CVE-2020-3923 being exploited?

CVE-2020-3923 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2020-3923 affect?

CVE-2020-3923 affects tat-77104g1 firmware, tat-70432n firmware, tat-71416g1 firmware. Severity is high (CVSS 8.1). DVR firmware in TAT-76 and TAT-77 series of products, provided by TONNET, contain misconfigured authentication mechanism. Attackers can crack the default password and gain access to the system.

How urgent is CVE-2020-3923?

Priority 53/100. High severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2020-3924 MEDIUM 6.4 UPGRADE UPGRADE DVR firmware in TAT-76 and TAT-77 series of products, provided by TONNET do not properly verify patch files

References

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