# CVE-2019-1891: Cisco Small Business Series Switches HTTP Denial of Service Vulnerability

> Unauthenticated remote attackers can cause a denial of service on Cisco Small Business switches by sending malicious requests to the web interface.

- **Severity:** High 7.5 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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:** 6 Jul 2019
- **Updated:** 19 Nov 2024
- **Also known as:** GHSA-8jqq-2p4j-9fgf

## What is CVE-2019-1891?

CVE-2019-1891 is a high-severity denial of service vulnerability in Cisco Small Business 300 Series Managed Switches, published on 6 Jul 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in the web interface of Cisco Small Business 200, 300, and 500 Series Managed Switches could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to improper validation of requests sent to the web interface. An attacker could exploit this vulnerability by sending a malicious request to the web interface of an affected device. A successful exploit could allow the attacker to cause an unexpected reload of the device, resulting in a DoS condition.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2019-1891?

It affects 57 products.


Products: Cisco Esw2-350g52dc Firmware, Cisco Esw2-550x48dc Firmware, Cisco Sf200-24 Firmware, Cisco Sf200-24p Firmware, Cisco Sf200-48 Firmware, Cisco Sf200-48p 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 Sf500-24 Firmware and 37 more.

## How do I fix CVE-2019-1891?

No fix has been published for CVE-2019-1891 yet. Limit exposure of the affected software until one is available.

## Is CVE-2019-1891 being exploited?

There is no known exploitation of CVE-2019-1891 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Small Business 300 Series Managed Switches

- [CVE-2019-1806](https://insights.sbomify.com/CVE-2019-1806/): Cisco Small Business Series Switches Simple Network Management Protocol Denial of Service Vulnerability (high 7.7)
- [CVE-2019-1892](https://insights.sbomify.com/CVE-2019-1892/): Cisco Small Business Series Switches Memory Corruption Vulnerability (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-1891 and fix it if it is affected.

What it is: CVE-2019-1891 is a high-severity denial of service vulnerability in Cisco Small Business 300 Series Managed Switches, published on 6 Jul 2019. 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-2019-1891 in the wild and no public exploit code.

Affected product: Cisco Small Business 300 Series 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-2019-1891/ (Markdown: https://insights.sbomify.com/CVE-2019-1891/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-1891
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-1891
- OSV: https://osv.dev/vulnerability/CVE-2019-1891

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From sbomify Insights: https://insights.sbomify.com/CVE-2019-1891/
Summaries are generated and may contain mistakes; the official description above is the record.