# CVE-2021-21891: Memory corruption in Lantronix

> An authenticated attacker can trigger a stack-based buffer overflow in the Web Manager to achieve remote code execution on Lantronix PremierWave devices.

- **Severity:** Critical 9.1 (`CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 22 Dec 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-c2pc-v7xf-jj54

## What is CVE-2021-21891?

CVE-2021-21891 is a critical memory corruption vulnerability in Lantronix, published on 22 Dec 2021. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

A stack-based buffer overflow vulnerability exists in the Web Manager FsBrowseClean functionality of Lantronix PremierWave 2050 8.9.0.0R4 (in QEMU). A specially crafted HTTP request can lead to remote code execution in the vulnerable portion of the branch (deletefile). An attacker can make an authenticated HTTP request to trigger this vulnerability.

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

## Which versions are affected by CVE-2021-21891?

It affects 1 product.


Products: Lantronix Premierwave 2050 Firmware.

## How do I fix CVE-2021-21891?

No fix has been published for CVE-2021-21891 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-21891 being exploited?

There is no known exploitation of CVE-2021-21891 in the wild and no public exploit code.

## Other vulnerabilities in Lantronix

- [CVE-2021-21872](https://insights.sbomify.com/CVE-2021-21872/): Command injection in Lantronix (critical 9.9)
- [CVE-2021-21881](https://insights.sbomify.com/CVE-2021-21881/): Command injection in Lantronix (critical 9.9)
- [CVE-2021-21882](https://insights.sbomify.com/CVE-2021-21882/): Command injection in Lantronix (critical 9.9)
- [CVE-2021-21883](https://insights.sbomify.com/CVE-2021-21883/): Command injection in Lantronix (critical 9.9)
- [CVE-2021-21889](https://insights.sbomify.com/CVE-2021-21889/): Memory corruption in Lantronix (critical 9.9)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-21891 and fix it if it is affected.

What it is: CVE-2021-21891 is a critical memory corruption vulnerability in Lantronix, published on 22 Dec 2021. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-21891 in the wild and no public exploit code.

Affected product: Lantronix. 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-2021-21891/ (Markdown: https://insights.sbomify.com/CVE-2021-21891/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-21891
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-21891
- OSV: https://osv.dev/vulnerability/CVE-2021-21891

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-21891/
Summaries are generated and may contain mistakes; the official description above is the record.