# CVE-2020-21991: Auth bypass in n/a

> Unauthenticated attackers can bypass authentication and gain admin access by manipulating the autologin parameter in the management interface.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/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:** 28 Apr 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-9c5r-2fv8-6qm7

## What is CVE-2020-21991?

CVE-2020-21991 is a critical authentication bypass vulnerability in n/a, published on 28 Apr 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

AVE DOMINAplus <=1.10.x suffers from an authentication bypass vulnerability due to missing control check when directly calling the autologin GET parameter in changeparams.php script. Setting the autologin value to 1 allows an unauthenticated attacker to permanently disable the authentication security control and access the management interface with admin privileges without providing credentials.

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2020-21991?

It affects 7 products.


Products: Ave 53ab-Wbs Firmware, Ave Dominaplus, Ave Ts01 Firmware, Ave Ts03x-v Firmware, Ave Ts04x-v Firmware, Ave Ts05 Firmware, Ave Ts05n-v Firmware.

## How do I fix CVE-2020-21991?

No fix has been published for CVE-2020-21991 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-21991 being exploited?

There is no known exploitation of CVE-2020-21991 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2020-21994](https://insights.sbomify.com/CVE-2020-21994/): Information disclosure in n/a (critical 9.8)
- [CVE-2020-21996](https://insights.sbomify.com/CVE-2020-21996/): Missing authorization in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-21991 and fix it if it is affected.

What it is: CVE-2020-21991 is a critical authentication bypass vulnerability in n/a, published on 28 Apr 2021. 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-2020-21991 in the wild and no public exploit code.

Affected product: n/a. 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-2020-21991/ (Markdown: https://insights.sbomify.com/CVE-2020-21991/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-21991
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-21991
- OSV: https://osv.dev/vulnerability/CVE-2020-21991

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-21991/
Summaries are generated and may contain mistakes; the official description above is the record.