# CVE-2026-109439: Lantronix XPress-DR 8.1.0.0 Unauthenticated Configuration Write via UDP 30718

> Remote attackers can read and persistently overwrite device configuration via unauthenticated UDP frames on Lantronix XPress-DR devices.

- **Severity:** Critical 9.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 14 Oct 2026
- **Updated:** 16 Oct 2026
- **Also known as:** GHSA-gpg6-w924-6c8v

## What is CVE-2026-109439?

CVE-2026-109439 is a critical missing authorization vulnerability in LANTRONIX XPress-DR, published on 14 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Lantronix XPress-DR and XPress-DR-I (CoBos-family) firmware through 8.1.0.0 contains a missing authentication vulnerability that allows remote attackers to read and persistently overwrite device configuration by sending crafted frames to the unauthenticated UDP configuration protocol on port 30718. Attackers can send a type 0xF8 query to read live configuration data and a type 0xFD frame with exactly 0x78 body bytes to rewrite the device IP address and serial-channel forwarding records, causing changes to commit to EEPROM and persist across reboots. The XPress-DR product series reached end-of-life/end-of-support in February 2025.

Weakness: CWE-306 (Missing Authentication for Critical Functionality)

## Which versions are affected by CVE-2026-109439?


## How do I fix CVE-2026-109439?

No fix has been published for CVE-2026-109439 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-109439 being exploited?

There is no known exploitation of CVE-2026-109439 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-109439 and fix it if it is affected.

What it is: CVE-2026-109439 is a critical missing authorization vulnerability in LANTRONIX XPress-DR, published on 14 Oct 2026. 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-2026-109439 in the wild and no public exploit code.

Affected product: LANTRONIX XPress-DR. 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-2026-109439/ (Markdown: https://insights.sbomify.com/CVE-2026-109439/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-109439
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-109439
- OSV: https://osv.dev/vulnerability/CVE-2026-109439

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-109439/
Summaries are generated and may contain mistakes; the official description above is the record.