# Siemens RUGGEDCOM ROX II authentication bypass via BIST

Published: 2025-08-14 · Severity: routine · Sectors: manufacturing
Canonical: https://vorant.io/reports/4a79381c-774b-5430-82dd-6544d32e12f3/siemens-ruggedcom-rox-ii-authentication-bypass-via-bist

> Authentication bypass in Siemens RUGGEDCOM ROX II allows local physical access to root shell; no fix available yet.

Siemens RUGGEDCOM ROX II industrial routers across all versions are vulnerable to an authentication bypass affecting 11 product variants including MX5000, RX1536, RX5000, and RX1400-RX1524 models. The vulnerability exists in the Built-In-Self-Test (BIST) mode, which does not properly restrict access via the serial interface. An attacker with physical access to the serial port can bypass authentication and gain root shell access to the device, compromising the confidentiality, integrity, and availability of the router. CVSS v4 score is 8.6 with low attack complexity. Siemens has not released a fix; the only available mitigation is to set a secure boot password as documented in product configuration manuals. The vulnerability is not remotely exploitable and no public exploitation has been reported to CISA.

## Mentioned in this report

- Vulnerabilities: CVE-2025-40761

Source reporting: https://www.cisa.gov/news-events/ics-advisories/icsa-25-226-20

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