CVE-2025-38676 Cert Portal CVE debrief

Who should care

Siemens SIMATIC CN 4100 owners and maintainers, OT security teams, Linux kernel integrators, and defenders responsible for embedded or appliance images that inherit the affected kernel code path.

Technical summary

According to the advisory text, the kernel command line is usually trusted, but the amd iommu code could overflow a stack buffer by one byte if the str argument reached maximum length. The issue is described as a stack buffer overflow in kernel code, with CVSS 3.1 vector AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:H. CISA’s republished advisory ties the issue to Siemens SIMATIC CN 4100 versions before 5.0 and points to Siemens ProductCERT SSA-032379 for remediation.

Defensive priority

Medium. The flaw is locally reachable and requires high privileges, but it affects kernel code and carries high integrity/availability impact in the published CVSS vector.

Recommended defensive actions

• Update Siemens SIMATIC CN 4100 to V5.0 or later, per Siemens guidance.
• Confirm whether your deployed images include the affected Linux kernel code path and whether the Siemens advisory applies to your environment.
• Track CISA advisory ICSA-26-134-10 and Siemens ProductCERT SSA-032379 for any product-specific remediation details.
• If you maintain customized builds, verify that the kernel fix for the iommu/amd acpiid handling is present in your software baseline.
• Use standard ICS defense-in-depth practices such as segmentation, least privilege, and controlled administrative access around affected assets.

Evidence notes

The source corpus shows CISA publication on 2026-05-12 and republication on 2026-05-14 from Siemens ProductCERT SSA-032379. The vulnerability description is limited to a one-byte stack overflow risk in iommu/amd when the command-line string is at maximum length. The product mapping in the advisory is marked low confidence and needs review.

Official resources