# CVE-2018-0197: Cisco IOS and IOS XE Software VLAN Trunking Protocol Denial of Service Vulnerability

> An adjacent attacker can cause a denial of service by sending crafted VTP packets to Cisco IOS devices in default server mode without a domain name.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:A/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:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 5 Oct 2018
- **Updated:** 26 Nov 2024
- **Also known as:** GHSA-r7rx-2r34-f26f

## What is CVE-2018-0197?

CVE-2018-0197 is a medium-severity denial of service vulnerability in Cisco Ios, published on 5 Oct 2018. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A vulnerability in the VLAN Trunking Protocol (VTP) subsystem of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, adjacent attacker to corrupt the internal VTP database on an affected device and cause a denial of service (DoS) condition. The vulnerability is due to a logic error in how the affected software handles a subset of VTP packets. An attacker could exploit this vulnerability by sending VTP packets in a sequence that triggers a timeout in the VTP message processing code of the affected software. A successful exploit could allow the attacker to impact the ability to create, modify, or delete VLANs and cause a DoS condition. There are workarounds that address this vulnerability. This vulnerability affects Cisco devices that are running a vulnerable release of Cisco IOS Software or Cisco IOS XE Software, are operating in VTP client mode or VTP server mode, and do not have a VTP domain name configured. The default configuration for Cisco devices that are running Cisco IOS Software or Cisco IOS XE Software and support VTP is to operate in VTP server mode with no domain name configured.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2018-0197?

It affects 2 products.


Products: Cisco Ios, Cisco Ios Xe.

## How do I fix CVE-2018-0197?

No fix has been published for CVE-2018-0197 yet. Limit exposure of the affected software until one is available.

## Is CVE-2018-0197 being exploited?

There is no known exploitation of CVE-2018-0197 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Ios

- [CVE-2017-12240](https://insights.sbomify.com/CVE-2017-12240/): Cisco IOS and IOS XE Software DHCP Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2017-3881](https://insights.sbomify.com/CVE-2017-3881/): Cisco IOS and IOS XE Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2018-0167](https://insights.sbomify.com/CVE-2018-0167/): Cisco IOS, XR, and XE Software Buffer Overflow (high 8.8, exploited in the wild)
- [CVE-2017-6736](https://insights.sbomify.com/CVE-2017-6736/): Cisco IOS and IOS XE Software SNMP Remote Code Execution (high 8.8, exploited in the wild)
- [CVE-2017-6737](https://insights.sbomify.com/CVE-2017-6737/): Cisco IOS and IOS XE Software SNMP Remote Code Execution (high 8.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-0197 and fix it if it is affected.

What it is: CVE-2018-0197 is a medium-severity denial of service vulnerability in Cisco Ios, published on 5 Oct 2018. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2018-0197 in the wild and no public exploit code.

Affected product: Cisco Ios. 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-2018-0197/ (Markdown: https://insights.sbomify.com/CVE-2018-0197/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-0197
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-0197
- OSV: https://osv.dev/vulnerability/CVE-2018-0197

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From sbomify Insights: https://insights.sbomify.com/CVE-2018-0197/
Summaries are generated and may contain mistakes; the official description above is the record.