# CVE-2021-34580: Remote user enumeration in mymbCONNECT24, mbCONNECT24 <= 2.9.0

> Unauthenticated attackers can enumerate valid backend users by analyzing server responses to invalid login attempts in mbCONNECT24.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 27 Oct 2021
- **Updated:** 17 Sep 2024
- **Also known as:** GHSA-v5p4-qxg5-3jh2

## What is CVE-2021-34580?

CVE-2021-34580 is a high-severity vulnerability in mbCONNECT24, published on 27 Oct 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In mymbCONNECT24, mbCONNECT24 <= 2.9.0 an unauthenticated user can enumerate valid backend users by checking what kind of response the server sends for crafted invalid login attempts.

Weakness: CWE-203 (Observable Discrepancy), CWE-204 (Observable Response Discrepancy)

## Which versions are affected by CVE-2021-34580?

It affects 2 products.


Products: Mbconnectline Mbconnect24, Mbconnectline Mymbconnect24.

## How do I fix CVE-2021-34580?

No fix has been published for CVE-2021-34580 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-34580 being exploited?

There is no known exploitation of CVE-2021-34580 in the wild and no public exploit code.

## Other vulnerabilities in mbCONNECT24

- [CVE-2020-35565](https://insights.sbomify.com/CVE-2020-35565/): Security feature bypass in n/a (critical 9.8)
- [CVE-2020-10383](https://insights.sbomify.com/CVE-2020-10383/): Code injection in n/a (critical 9.8)
- [CVE-2026-33615](https://insights.sbomify.com/CVE-2026-33615/): MB connect line mbCONNECT24 vulnerable to an unauthenticated SQL injection in the setinfo Endpoint (critical 9.1)
- [CVE-2023-0985](https://insights.sbomify.com/CVE-2023-0985/): Helmholz and MB Connect Line: Account takeover via password reset in multiple products (high 8.8)
- [CVE-2020-10382](https://insights.sbomify.com/CVE-2020-10382/): Code injection in n/a (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-34580 and fix it if it is affected.

What it is: CVE-2021-34580 is a high-severity vulnerability in mbCONNECT24, published on 27 Oct 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-2021-34580 in the wild and no public exploit code.

Affected product: mbCONNECT24. 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-2021-34580/ (Markdown: https://insights.sbomify.com/CVE-2021-34580/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-34580
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-34580
- OSV: https://osv.dev/vulnerability/CVE-2021-34580

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-34580/
Summaries are generated and may contain mistakes; the official description above is the record.