# CVE-2020-4042: Authentication bypass in Bareos

> A malicious client can bypass authentication in Bareos by replaying challenges, allowing unauthorized communication with the director.

- **Severity:** Medium 6.8 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 10 Jul 2020
- **Updated:** 4 Aug 2024
- **Also known as:** CLEANSTART-2024-ZR44827, GHSA-vqpj-2vhj-h752, UBUNTU-CVE-2020-4042

## What is CVE-2020-4042?

CVE-2020-4042 is a medium-severity authentication bypass vulnerability in bareos, published on 10 Jul 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Bareos before version 19.2.8 and earlier allows a malicious client to communicate with the director without knowledge of the shared secret if the director allows client initiated connection and connects to the client itself. The malicious client can replay the Bareos director's cram-md5 challenge to the director itself leading to the director responding to the replayed challenge. The response obtained is then a valid reply to the directors original challenge. This is fixed in version 19.2.8.

Weakness: CWE-294 (Authentication Bypass by Capture-replay)

## Which versions are affected by CVE-2020-4042?

It affects 1 product.


Products: Bareos Bareos.

## How do I fix CVE-2020-4042?

Upgrade to a fixed version.

## Is CVE-2020-4042 being exploited?

There is no known exploitation of CVE-2020-4042 in the wild and no public exploit code.

## Other vulnerabilities in bareos

- [CVE-2022-24755](https://insights.sbomify.com/CVE-2022-24755/): Incorrect Authorization in Bareos Director (high 8.1)
- [CVE-2017-14610](https://insights.sbomify.com/CVE-2017-14610/): Race condition in n/a (high 7.8)
- [CVE-2022-24756](https://insights.sbomify.com/CVE-2022-24756/): Missing Release of Memory after Effective Lifetime in Bareos Director (high 7.5)
- [CVE-2020-11061](https://insights.sbomify.com/CVE-2020-11061/): Heap-based Buffer Overflow in Bareos Director (medium 6.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-4042 and fix it if it is affected.

What it is: CVE-2020-4042 is a medium-severity authentication bypass vulnerability in bareos, published on 10 Jul 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-2020-4042 in the wild and no public exploit code.

Affected product: bareos. 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-2020-4042/ (Markdown: https://insights.sbomify.com/CVE-2020-4042/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-4042
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-4042
- OSV: https://osv.dev/vulnerability/CVE-2020-4042

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-4042/
Summaries are generated and may contain mistakes; the official description above is the record.