PatchSiren

PatchSiren cyber security CVE debrief

CVE-2024-43893 Siemens CVE debrief

A divide-by-zero vulnerability exists in the Linux serial core subsystem when the TIOCSSERIAL ioctl is called with an invalid baud_base parameter. The flaw stems from a missing validation check for uartclk being zero, which can trigger a divide-by-zero error. This vulnerability affects Siemens industrial networking products running SINEC OS, specifically the RUGGEDCOM RST2428P and SCALANCE X-family switches. The issue was initially published on August 12, 2025, with subsequent advisory updates through February 2026 to correct affected product listings and clarify configuration details. Siemens has assessed the impact as 'Misinformed' for the affected products, indicating the vulnerability's applicability may be limited or mischaracterized in certain contexts. No known exploitation in ransomware campaigns has been reported.

Vendor
Siemens
Product
RUGGEDCOM RST2428P (6GK6242-6PA00)
CVSS
MEDIUM 5.5
CISA KEV
Not listed in stored evidence
Original CVE published
2025-08-12
Original CVE updated
2026-02-25
Advisory published
2025-08-12
Advisory updated
2026-02-25

Who should care

Organizations operating Siemens RUGGEDCOM RST2428P switches or SCALANCE X-family industrial Ethernet switches in critical infrastructure, manufacturing, or utility environments. Security teams responsible for OT/ICS asset management and Linux kernel security in embedded industrial systems.

Technical summary

The vulnerability resides in the Linux kernel's serial core implementation where uartclk validation is absent. When userspace invokes the TIOCSSERIAL ioctl with a baud_base value that results in uartclk being zero, the subsequent division operation triggers a kernel-level divide-by-zero condition. This represents a local denial-of-service vector requiring privileged access to serial device nodes. The affected Siemens products incorporate this kernel component through their SINEC OS foundation.

Defensive priority

medium

Recommended defensive actions

  • Review Siemens ProductCERT advisory SSA-355557 for detailed product-specific impact assessment and configuration guidance
  • Verify SCALANCE XC-300/XR-300/XC-400/XR-500WG/XR-500 family configuration to determine actual exposure per February 2026 advisory clarification
  • Apply vendor-provided patches or firmware updates when available for affected SINEC OS-based products
  • Implement network segmentation for industrial control systems per CISA recommended practices
  • Monitor serial interface access controls to restrict unauthorized TIOCSSERIAL ioctl calls
  • Assess operational technology environments for Linux-based systems utilizing serial core drivers

Evidence notes

Vulnerability description derived from CISA ICS advisory ICSA-25-226-07 and Siemens ProductCERT SSA-355557. Impact assessment of 'Misinformed' sourced directly from CSAF threat data. Advisory revision history confirms multiple updates through February 2026 for product clarification.

Sources and references

Verified primary and authoritative sources

  • CVE-2024-43893 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2024-43893

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2024-43893 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2024-43893

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • Source item URL

    Unverified legacy reference

    URL: https://raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/OT/white/2025/icsa-25-226-07.json

    cisa_csaf

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/csaf/ssa-355557.json

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/html/ssa-355557.html

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/news-events/ics-advisories/icsa-25-226-07

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/news-events/ics-alerts/ics-alert-10-301-01

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/resources-tools/resources/ics-recommended-practices

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/topics/industrial-control-systems

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/sites/default/files/recommended_practices/NCCIC_ICS-CERT_Defense_in_Depth_2016_S508C.pdf

    Reference

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.