# CVE-2018-25235: NetworkActiv Web Server 4.0 Username Field Buffer Overflow DoS

> Local attackers can crash NetworkActiv Web Server by supplying an excessively long username string, causing a denial of service.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **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:** 30 Mar 2026
- **Updated:** 30 Mar 2026
- **Also known as:** GHSA-x4g8-cm9x-f937

## What is CVE-2018-25235?

CVE-2018-25235 is a medium-severity memory corruption vulnerability in NetworkActiv Web Server, published on 30 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

NetworkActiv Web Server 4.0 contains a buffer overflow vulnerability in the username field of the Security options that allows local attackers to crash the application by supplying an excessively long string. Attackers can trigger a denial of service by entering a crafted username value exceeding the expected buffer size through the Set username interface.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2018-25235?

It affects 1 product.


Products: Networkactiv Web Server.

## How do I fix CVE-2018-25235?

No fix has been published for CVE-2018-25235 yet. Limit exposure of the affected software until one is available.

## Is CVE-2018-25235 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2018-25235 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-25235 and fix it if it is affected.

What it is: CVE-2018-25235 is a medium-severity memory corruption vulnerability in NetworkActiv Web Server, published on 30 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2018-25235 exists.

Affected product: NetworkActiv Web Server. 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-2018-25235/ (Markdown: https://insights.sbomify.com/CVE-2018-25235/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-25235
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-25235
- OSV: https://osv.dev/vulnerability/CVE-2018-25235

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-25235/
Summaries are generated and may contain mistakes; the official description above is the record.