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PatchSiren cyber security CVE debrief

CVE-2026-25656 Siemens CVE debrief

CVE-2026-25656 is a high-severity local privilege-escalation issue affecting Siemens SINEC NMS and the User Management Component (UMC). According to the CISA-republished Siemens advisory, a low-privileged user can improperly modify a configuration file, which may allow malicious DLL loading and potentially lead to arbitrary code execution with SYSTEM privileges. Siemens has issued fixed versions for the affected product lines, and defenders should prioritize patching on hosts where local users or service accounts are present.

Vendor
Siemens
Product
SINEC NMS
CVSS
HIGH 7.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-02-10
Original CVE updated
2026-04-16
Advisory published
2026-02-10
Advisory updated
2026-04-16

Who should care

Administrators and security teams responsible for Siemens SINEC NMS and UMC deployments, especially on Windows systems that allow local logons, shared administration, or low-privileged user access.

Technical summary

The published advisory describes a configuration-file integrity weakness that can be abused by a low-privileged local user. The stated outcome is malicious DLL loading and possible code execution with SYSTEM privileges. The supplied CVSS v3.1 vector is AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H, consistent with a local attack that can materially affect confidentiality, integrity, and availability once exploitation conditions are met.

Defensive priority

High; prioritize patching on any exposed SINEC NMS or UMC system where local user access exists.

Recommended defensive actions

  • Update Siemens SINEC NMS to V2.15.2.1 or later, or to V4.0 SP3 or later, depending on the installed product line.
  • Restrict low-privileged local access on affected hosts until remediation is complete.
  • Review permissions on application configuration files and related directories to ensure standard users cannot modify them.
  • Monitor affected systems for unexpected DLL loading behavior and unauthorized changes to application configuration files.
  • Follow CISA ICS recommended practices and defense-in-depth guidance for industrial control environments.

Evidence notes

The source corpus is a CISA CSAF republication of Siemens ProductCERT advisory SSA-311973 for ICSA-26-043-01, published 2026-02-10 and updated through 2026-04-16. The description, product names, and remediations are taken from the supplied advisory metadata. The enrichment marks this as not listed in CISA KEV. No exploit code or offensive instructions are included.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-25656 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-25656

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

  • CVE-2026-25656 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-25656

    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/2026/icsa-26-043-01.json

    cisa_csaf

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/csaf/ssa-311973.json

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/html/ssa-311973.html

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/news-events/ics-advisories/icsa-26-043-01

    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.