CVE-2026-54548: CVE-2026-54548: Persistent SSH Host Key Checking Disablement in Siemens kas

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CVE-2026-54548: Persistent SSH Host Key Checking Disablement in Siemens kas

Vulnerability ID: CVE-2026-54548
CVSS Score: 3.3
Published: 2026-08-26

Prior to version 5.4, the Siemens kas setup utility unconditionally disabled SSH host key verification globally within the invoking user's persistent ~/.ssh/config file when utilizing SSH keys. This configuration degradation persists after execution, leaving subsequent user SSH connections vulnerable to Man-in-the-Middle (MitM) attacks.

TL;DR

Siemens kas versions prior to 5.4 persistently disable SSH host key verification globally on host workstations, creating an indefinite susceptibility to Man-in-the-Middle (MitM) attacks.

⚠️ Exploit Status: POC

Technical Details

CWE ID: CWE-295
Attack Vector: Local (AV:L)
CVSS Score: 3.3
EPSS Score: 0.00
Impact: Transport Integrity and Confidentiality Degradation
Exploit Status: poc
KEV Status: Not Listed

Affected Systems

Siemens kas setup and orchestration utility
kas: < 5.4 (Fixed in: 5.4)

Code Analysis

Commit: 1c1e861

Fix: restrict SSH host key checking disablement to externally managed environments

Mitigation Strategies

Upgrade kas to version 5.4 or newer
Regularly inspect local ~/.ssh/config configurations
Enforce ephemeral containerized execution environments for build orchestration tools

Remediation Steps:

Upgrade kas via pip: pip install --upgrade kas
Verify and clean up local ~/.ssh/config file: remove the wildcard directive (Host *) that disables StrictHostKeyChecking
For automated environments, ensure build runners are strictly container-based and short-lived

References

Read the full report for CVE-2026-54548 on our website for more details including interactive diagrams and full exploit analysis.

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