# CVE-2019-1859: Cisco Small Business Switches Secure Shell Certificate Authentication Bypass Vulnerability

> Attacker bypasses SSH certificate authentication to gain administrative access if default credentials are unchanged, requiring disabling certificate auth as mitigation.

- **Severity:** High 7.2 (`CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 3 May 2019
- **Updated:** 20 Nov 2024
- **Also known as:** GHSA-vxf6-wwjr-wqh4

## What is CVE-2019-1859?

CVE-2019-1859 is a high-severity authentication bypass vulnerability in Cisco Small Business 200 Series Smart Switches, published on 3 May 2019. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

A vulnerability in the Secure Shell (SSH) authentication process of Cisco Small Business Switches software could allow an attacker to bypass client-side certificate authentication and revert to password authentication. The vulnerability exists because OpenSSH mishandles the authentication process. An attacker could exploit this vulnerability by attempting to connect to the device via SSH. A successful exploit could allow the attacker to access the configuration as an administrative user if the default credentials are not changed. There are no workarounds available; however, if client-side certificate authentication is enabled, disable it and use strong password authentication. Client-side certificate authentication is disabled by default.

Weakness: CWE-295 (Improper Certificate Validation), CWE-285 (Improper Authorization)

## Which versions are affected by CVE-2019-1859?

It affects 114 products.


Products: Cisco Sf200-24 Firmware, Cisco Sf200-24fp Firmware, Cisco Sf200-24p Firmware, Cisco Sf200-48 Firmware, Cisco Sf200-48p Firmware, Cisco Sf250-24 Firmware, Cisco Sf250-24p Firmware, Cisco Sf250-48 Firmware, Cisco Sf250-48hp Firmware, Cisco Sf300-08 Firmware, Cisco Sf300-24 Firmware, Cisco Sf300-24mp Firmware, Cisco Sf300-24p Firmware, Cisco Sf300-24pp Firmware, Cisco Sf300-48 Firmware, Cisco Sf300-48p Firmware, Cisco Sf300-48pp Firmware, Cisco Sf302-08 Firmware, Cisco Sf302-08mp Firmware, Cisco Sf302-08mpp Firmware and 94 more.

## How do I fix CVE-2019-1859?

No fix has been published for CVE-2019-1859 yet. Limit exposure of the affected software until one is available.

## Is CVE-2019-1859 being exploited?

There is no known exploitation of CVE-2019-1859 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Small Business 200 Series Smart Switches

- [CVE-2018-15439](https://insights.sbomify.com/CVE-2018-15439/): Cisco Small Business Switches Privileged Access Vulnerability (critical 9.8)
- [CVE-2020-3363](https://insights.sbomify.com/CVE-2020-3363/): Cisco Small Business Smart and Managed Switches Denial of Service Vulnerability (high 8.6)
- [CVE-2020-3297](https://insights.sbomify.com/CVE-2020-3297/): Cisco Small Business Smart and Managed Switches Session Management Vulnerability (high 8.1)
- [CVE-2019-12636](https://insights.sbomify.com/CVE-2019-12636/): Cisco Small Business Smart and Managed Switches Cross-Site Request Forgery Vulnerability (high 8.1)
- [CVE-2019-15993](https://insights.sbomify.com/CVE-2019-15993/): Cisco Small Business Switches Information Disclosure Vulnerability (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-1859 and fix it if it is affected.

What it is: CVE-2019-1859 is a high-severity authentication bypass vulnerability in Cisco Small Business 200 Series Smart Switches, published on 3 May 2019. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2019-1859 in the wild and no public exploit code.

Affected product: Cisco Small Business 200 Series Smart Switches. 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-2019-1859/ (Markdown: https://insights.sbomify.com/CVE-2019-1859/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-1859
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-1859
- OSV: https://osv.dev/vulnerability/CVE-2019-1859

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-1859/
Summaries are generated and may contain mistakes; the official description above is the record.