# CVE-2018-21165: Denial of service in n/a

> Attackers can cause a denial of service on various NETGEAR routers, requiring firmware updates to mitigate.

- **Severity:** Medium 4.5 (`CVSS:3.0/AC:L/AV:A/A:H/C:N/I:N/PR:H/S:U/UI:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 23 Apr 2020
- **Updated:** 5 Aug 2024
- **Also known as:** GHSA-j823-9vj8-r736

## What is CVE-2018-21165?

CVE-2018-21165 is a medium-severity denial of service vulnerability in Netgear R6100 Firmware, published on 23 Apr 2020. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Certain NETGEAR devices are affected by denial of service. This affects R6100 before 1.0.1.22, R7500 before 1.0.0.122, R7800 before 1.0.2.42, R8900 before 1.0.3.10, R9000 before 1.0.3.10, WNDR3700v4 before 1.0.2.96, WNDR4300 before 1.0.2.98, WNDR4300v2 before 1.0.0.54, WNDR4500v3 before 1.0.0.54, and WNR2000v5 before 1.0.0.64.

## Which versions are affected by CVE-2018-21165?

It affects 9 products.


Products: Netgear R6100 Firmware, Netgear R7500 Firmware, Netgear R7800 Firmware, Netgear R8900 Firmware, Netgear R9000 Firmware, Netgear Wndr3700 Firmware, Netgear Wndr4300 Firmware, Netgear Wndr4500 Firmware, Netgear Wnr2000 Firmware.

## How do I fix CVE-2018-21165?

No fix has been published for CVE-2018-21165 yet. Limit exposure of the affected software until one is available.

## Is CVE-2018-21165 being exploited?

There is no known exploitation of CVE-2018-21165 in the wild and no public exploit code.

## Other vulnerabilities in Netgear R6100 Firmware

- [CVE-2025-29044](https://insights.sbomify.com/CVE-2025-29044/): Memory corruption in n/a (critical 9.8)
- [CVE-2018-21203](https://insights.sbomify.com/CVE-2018-21203/): Memory corruption in n/a (high 8.8)
- [CVE-2017-18775](https://insights.sbomify.com/CVE-2017-18775/): Cross-site request forgery in n/a (high 8.8)
- [CVE-2017-18698](https://insights.sbomify.com/CVE-2017-18698/): Memory corruption in n/a (medium 6.8)
- [CVE-2017-18706](https://insights.sbomify.com/CVE-2017-18706/): Misconfiguration in n/a (medium 6.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-21165 and fix it if it is affected.

What it is: CVE-2018-21165 is a medium-severity denial of service vulnerability in Netgear R6100 Firmware, published on 23 Apr 2020. 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-2018-21165 in the wild and no public exploit code.

Affected product: Netgear R6100 Firmware. 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-2018-21165/ (Markdown: https://insights.sbomify.com/CVE-2018-21165/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-21165
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-21165
- OSV: https://osv.dev/vulnerability/CVE-2018-21165

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-21165/
Summaries are generated and may contain mistakes; the official description above is the record.