# CVE-2026-34021: Lack of cryptographic protection in Wertheim SafeController 5400 enables RS-485 message sniffing and replay

> Attackers can sniff and replay unencrypted RS-485 messages to spoof alarm deactivation commands on Wertheim SafeController 5400 systems.

- **Severity:** High 8.6 (`CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/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:** 15 Jun 2026
- **Updated:** 15 Jun 2026
- **Also known as:** GHSA-4w8g-q38j-gm8m

## What is CVE-2026-34021?

CVE-2026-34021 is a high-severity vulnerability in Wertheim SafeController 5400 Hardware for VAULT ROOMS (Safe Deposit Locker System - Microcontroller), published on 15 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

The Wertheim SafeController 5400, Controller 5400 - AssemblyVersion 6.11.8130.22320, uses RS-485 communication between the server and the microcontroller without cryptographic protection. An attacker with access to the communication path between the server and the microcontroller can sniff RS-485 messages and replay previously observed messages. This can be used, for example, to spoof a "quit alarm" message and continuously deactivate the safe alarm.

Weakness: CWE-294 (Authentication Bypass by Capture-replay)

## Which versions are affected by CVE-2026-34021?


## How do I fix CVE-2026-34021?

No fix has been published for CVE-2026-34021 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-34021 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-34021 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-34021 and fix it if it is affected.

What it is: CVE-2026-34021 is a high-severity vulnerability in Wertheim SafeController 5400 Hardware for VAULT ROOMS (Safe Deposit Locker System - Microcontroller), published on 15 Jun 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-2026-34021 exists.

Affected product: Wertheim SafeController 5400 Hardware for VAULT ROOMS (Safe Deposit Locker System - Microcontroller). 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-2026-34021/ (Markdown: https://insights.sbomify.com/CVE-2026-34021/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-34021
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-34021
- OSV: https://osv.dev/vulnerability/CVE-2026-34021

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-34021/
Summaries are generated and may contain mistakes; the official description above is the record.