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PatchSiren cyber security CVE debrief

CVE-2025-21669 Siemens CVE debrief

A vulnerability in the vsock/virtio transport layer of the Linux kernel could allow a local attacker to cause a denial-of-service condition. The flaw occurs when the virtio transport changes during packet processing, potentially leading to improper packet handling. This affects Siemens SIMATIC S7-1500 TM MFP industrial control systems that utilize the GNU/Linux subsystem. The vulnerability requires local access with low privileges and has no impact on confidentiality or integrity, but can result in high availability impact.

Vendor
Siemens
Product
SIMATIC S7-1500 TM MFP - GNU/Linux subsystem
CVSS
HIGH 7.8
CISA KEV
Not listed in stored evidence
Original CVE published
2025-01-31
Original CVE updated
2026-07-30
Advisory published
2025-01-31
Advisory updated
2026-07-30

Who should care

Industrial control system operators, OT security teams, and organizations deploying Siemens SIMATIC S7-1500 TM MFP controllers in manufacturing, process control, or critical infrastructure environments. System integrators and maintenance personnel with access to the GNU/Linux subsystem should be aware of access control requirements.

Technical summary

The vulnerability exists in the vsock/virtio transport implementation within the Linux kernel. When the virtio transport changes during packet processing, packets may not be properly discarded, leading to potential denial-of-service conditions. This affects the GNU/Linux subsystem on Siemens SIMATIC S7-1500 TM MFP programmable logic controllers. The CVSS 3.1 score of 5.5 (MEDIUM) reflects a local attack vector requiring low privileges, with high impact to availability but no impact to confidentiality or integrity. No patch is currently available; mitigation relies on access controls and trusted application execution.

Defensive priority

medium

Recommended defensive actions

  • Restrict interactive shell access to the GNU/Linux subsystem to trusted personnel only
  • Implement application allowlisting - only build and run applications from trusted sources
  • Monitor for anomalous local process activity on affected Siemens SIMATIC S7-1500 TM MFP systems
  • Apply defense-in-depth strategies for industrial control system environments per CISA guidance
  • Establish network segmentation to limit lateral movement from compromised endpoints
  • Review and implement ICS-CERT recommended practices for securing industrial control systems

Evidence notes

CVE published 2024-04-09 per CISA CSAF advisory ICSA-24-102-01. Advisory subsequently updated multiple times through 2025-09-09 with additional CVEs. CVSS 3.1 vector AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H confirms local attack vector with availability impact only.

Sources and references

Verified primary and authoritative sources

  • CVE-2025-21669 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2025-21669

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

  • CVE-2025-21669 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2025-21669

    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/2024/icsa-24-102-01.json

    cisa_csaf

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/csaf/ssa-265688.json

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/html/ssa-265688.html

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/news-events/ics-advisories/icsa-24-102-01

    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.