# CVE-2020-3923: TONNET DVR – Broken Access Control

> Attackers can bypass authentication by cracking default passwords to gain unauthorized access to TONNET DVR systems.

- **Severity:** High 8.1 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 27 Feb 2020
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-jvq4-xpx6-3rjc

## What is CVE-2020-3923?

CVE-2020-3923 is a high-severity authentication bypass vulnerability in TONNET DVR, published on 27 Feb 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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.

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2020-3923?

It affects 8 products.


Products: Tonnet Tat-70432n Firmware, Tonnet Tat-71416g1 Firmware, Tonnet Tat-71832g1 Firmware, Tonnet Tat-76104g3 Firmware, Tonnet Tat-76108g3 Firmware, Tonnet Tat-76116g3 Firmware, Tonnet Tat-76132g3 Firmware, Tonnet Tat-77104g1 Firmware.

## How do I fix CVE-2020-3923?

No fix has been published for CVE-2020-3923 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-3923 being exploited?

There is no known exploitation of CVE-2020-3923 in the wild and no public exploit code.

## Other vulnerabilities in TONNET DVR

- [CVE-2020-3924](https://insights.sbomify.com/CVE-2020-3924/): TONNET DVR – Firmware Injection (medium 6.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-3923 and fix it if it is affected.

What it is: CVE-2020-3923 is a high-severity authentication bypass vulnerability in TONNET DVR, published on 27 Feb 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2020-3923 in the wild and no public exploit code.

Affected product: TONNET DVR. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2020-3923/ (Markdown: https://insights.sbomify.com/CVE-2020-3923/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-3923
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-3923
- OSV: https://osv.dev/vulnerability/CVE-2020-3923

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-3923/
Summaries are generated and may contain mistakes; the official description above is the record.