# CVE-2017-6720: Denial of service in Cisco Small Business Managed Switches

> An authenticated remote attacker can cause a denial of service on Cisco Small Business Managed Switches by sending a malicious SSH message.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 21 Sep 2017
- **Updated:** 5 Aug 2024
- **Also known as:** GHSA-vgpr-hxgc-qpwh

## What is CVE-2017-6720?

CVE-2017-6720 is a medium-severity denial of service vulnerability in Cisco Small Business Managed Switches, published on 21 Sep 2017. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A vulnerability in the Secure Shell (SSH) subsystem of Cisco Small Business Managed Switches software could allow an authenticated, remote attacker to cause a reload of the affected switch, resulting in a denial of service (DoS) condition. The vulnerability is due to improper processing of SSH connections. An attacker could exploit this vulnerability by logging in to an affected switch via SSH and sending a malicious SSH message. This vulnerability affects the following Cisco products when SSH is enabled: Small Business 300 Series Managed Switches, Small Business 500 Series Stackable Managed Switches, 350 Series Managed Switches, 350X Series Stackable Managed Switches, 550X Series Stackable Managed Switches, ESW2 Series Advanced Switches. Cisco Bug IDs: CSCvb48377.

Weakness: CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2017-6720?

It affects 85 products.


Products: Cisco Esw2-350g-52 Firmware, Cisco Esw2-350g-52dc Firmware, Cisco Esw2-550x-48 Firmware, Cisco Esw2-550x-48dc 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, Cisco Sf302-08p Firmware, Cisco Sf302-08pp Firmware, Cisco Sf350-48 Firmware, Cisco Sf350-48mp Firmware, Cisco Sf350-48p Firmware and 65 more.

## How do I fix CVE-2017-6720?

No fix has been published for CVE-2017-6720 yet. Limit exposure of the affected software until one is available.

## Is CVE-2017-6720 being exploited?

There is no known exploitation of CVE-2017-6720 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Small Business Managed Switches

- [CVE-2017-12307](https://insights.sbomify.com/CVE-2017-12307/): Cross-site scripting in Cisco Small Business 300 and 500 Series Managed Switches (medium 6.1)
- [CVE-2017-12308](https://insights.sbomify.com/CVE-2017-12308/): Cross-site scripting in Cisco Small Business 300 and 500 Series Managed Switches (medium 6.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2017-6720 and fix it if it is affected.

What it is: CVE-2017-6720 is a medium-severity denial of service vulnerability in Cisco Small Business Managed Switches, published on 21 Sep 2017. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2017-6720 in the wild and no public exploit code.

Affected product: Cisco Small Business Managed 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-2017-6720/ (Markdown: https://insights.sbomify.com/CVE-2017-6720/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2017-6720
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2017-6720
- OSV: https://osv.dev/vulnerability/CVE-2017-6720

---
From sbomify Insights: https://insights.sbomify.com/CVE-2017-6720/
Summaries are generated and may contain mistakes; the official description above is the record.