# CVE-2018-0239: Denial of service in Cisco StarOS

> Remote attackers can cause denial of service on Cisco ASR 5700 and VPC devices by sending crafted packets, requiring manual reload if a virtual interface card is installed.

- **Severity:** High 7.5 (`CVSS:3.1/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:** 19 Apr 2018
- **Updated:** 29 Nov 2024
- **Also known as:** GHSA-fr97-4833-96q9

## What is CVE-2018-0239?

CVE-2018-0239 is a high-severity denial of service vulnerability in Cisco StarOS, published on 19 Apr 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in the egress packet processing functionality of the Cisco StarOS operating system for Cisco Aggregation Services Router (ASR) 5700 Series devices and Virtualized Packet Core (VPC) System Software could allow an unauthenticated, remote attacker to cause an interface on the device to cease forwarding packets. The device may need to be manually reloaded to clear this Interface Forwarding Denial of Service condition. The vulnerability is due to the failure to properly check that the length of a packet to transmit does not exceed the maximum supported length of the network interface card (NIC). An attacker could exploit this vulnerability by sending a crafted IP packet or a series of crafted IP fragments through an interface on the targeted device. A successful exploit could allow the attacker to cause the network interface to cease forwarding packets. This vulnerability could be triggered by either IPv4 or IPv6 network traffic. This vulnerability affects the following Cisco products when they are running the StarOS operating system and a virtual interface card is installed on the device: Aggregation Services Router (ASR) 5700 Series, Virtualized Packet Core-Distributed Instance (VPC-DI) System Software, Virtualized Packet Core-Single Instance (VPC-SI) System Software. Cisco Bug IDs: CSCvf32385.

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling), CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2018-0239?

It affects 1 product.


Products: Cisco Staros.

## How do I fix CVE-2018-0239?

No fix has been published for CVE-2018-0239 yet. Limit exposure of the affected software until one is available.

## Is CVE-2018-0239 being exploited?

There is no known exploitation of CVE-2018-0239 in the wild and no public exploit code.

Public exploit code:

- /CSCOE/ CSCOV (github_poc): https://github.com/tpdlshdmlrkfmcla/CVE-2018-0239

## Other vulnerabilities in Cisco StarOS

- [CVE-2023-20046](https://insights.sbomify.com/CVE-2023-20046/): Auth bypass in Cisco ASR 5000 Series Software (high 8.8)
- [CVE-2019-1869](https://insights.sbomify.com/CVE-2019-1869/): Cisco StarOS Denial of Service Vulnerability (high 8.6)
- [CVE-2018-0369](https://insights.sbomify.com/CVE-2018-0369/): Denial of service in Cisco StarOS unknown (high 8.6)
- [CVE-2017-6707](https://insights.sbomify.com/CVE-2017-6707/): Command injection in Cisco StarOS (high 8.2)
- [CVE-2021-1539](https://insights.sbomify.com/CVE-2021-1539/): Cisco ASR 5000 Series Software Authorization Bypass Vulnerabilities (high 8.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-0239 and fix it if it is affected.

What it is: CVE-2018-0239 is a high-severity denial of service vulnerability in Cisco StarOS, published on 19 Apr 2018. 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-2018-0239 in the wild and no public exploit code.

Affected product: Cisco StarOS. 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-2018-0239/ (Markdown: https://insights.sbomify.com/CVE-2018-0239/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-0239
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-0239
- OSV: https://osv.dev/vulnerability/CVE-2018-0239

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-0239/
Summaries are generated and may contain mistakes; the official description above is the record.