# CVE-2021-32976: Moxa NPort IAW5000A-I/O Series Serial Device Server Stack-based Buffer Overflow

> Remote attackers can exploit stack-based buffer overflows in the web server to execute arbitrary code or cause denial of service on Moxa serial device servers.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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:** 1 Apr 2022
- **Updated:** 16 Apr 2025
- **Also known as:** GHSA-gr95-77pj-2gv2

## What is CVE-2021-32976?

CVE-2021-32976 is a critical memory corruption vulnerability in Moxa NPort IAW5000A-I/O series firmware, published on 1 Apr 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Five buffer overflows in the built-in web server in Moxa NPort IAW5000A-I/O series firmware version 2.2 or earlier may allow a remote attacker to initiate a denial-of-service attack and execute arbitrary code.

Weakness: CWE-787 (Out-of-bounds Write), CWE-121 (Stack-based Buffer Overflow)

## Which versions are affected by CVE-2021-32976?

It affects 4 products.


Products: Moxa Nport Iaw5150a-12i\/O Firmware, Moxa Nport Iaw5150a-6i\/O Firmware, Moxa Nport Iaw5250a-12i\/O Firmware, Moxa Nport Iaw5250a-6i\/O Firmware.

## How do I fix CVE-2021-32976?

No fix has been published for CVE-2021-32976 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-32976 being exploited?

There is no known exploitation of CVE-2021-32976 in the wild and no public exploit code.

## Other vulnerabilities in Moxa NPort IAW5000A-I/O series firmware

- [CVE-2021-32974](https://insights.sbomify.com/CVE-2021-32974/): Moxa NPort IAW5000A-I/O Series Serial Device Server Improper Input Validation (critical 9.8)
- [CVE-2021-32968](https://insights.sbomify.com/CVE-2021-32968/): Moxa NPort IAW5000A-I/O Series Serial Device Server Classic Buffer Overflow (high 7.5)
- [CVE-2021-32970](https://insights.sbomify.com/CVE-2021-32970/): Moxa NPort IAW5000A-I/O Series Serial Device Server Improper Input Validation (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-32976 and fix it if it is affected.

What it is: CVE-2021-32976 is a critical memory corruption vulnerability in Moxa NPort IAW5000A-I/O series firmware, published on 1 Apr 2022. 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-2021-32976 in the wild and no public exploit code.

Affected product: Moxa NPort IAW5000A-I/O series 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-2021-32976/ (Markdown: https://insights.sbomify.com/CVE-2021-32976/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-32976
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-32976
- OSV: https://osv.dev/vulnerability/CVE-2021-32976

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-32976/
Summaries are generated and may contain mistakes; the official description above is the record.