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PatchSiren cyber security CVE debrief

CVE-2025-7425 Siemens CVE debrief

CVE-2025-7425 is a high-severity memory-corruption issue in libxslt affecting Siemens SIMATIC CN 4100 versions before 5.0. Under certain XSLT processing paths, including key()-related tree fragments, the flaw can lead to improper cleanup of ID attributes, use-after-free crashes, or heap corruption.

Vendor
Siemens
Product
SIMATIC CN 4100
CVSS
HIGH 7.8
CISA KEV
Not listed in stored evidence
Original CVE published
2025-07-10
Original CVE updated
2026-09-21
Advisory published
2025-07-10
Advisory updated
2026-09-21

Who should care

Owners and operators of Siemens SIMATIC CN 4100 systems running versions earlier than 5.0, plus ICS security and patch-management teams responsible for those environments. Teams using libxslt-backed XSLT processing in affected deployments should also review exposure.

Technical summary

The advisory describes a flaw in libxslt where attribute type, atype, and flags are modified in a way that corrupts internal memory management. When XSLT functions such as key() produce tree fragments, ID attribute cleanup can be mishandled, leaving freed memory accessible. The supplied CVSS vector (AV:L/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:H) indicates local attack conditions, high complexity, no privileges or user interaction, and potential impact to integrity and availability.

Defensive priority

High. Prioritize affected Siemens SIMATIC CN 4100 systems for upgrade to V5.0 or later during the next maintenance window, with extra urgency in environments where the product is operationally critical.

Recommended defensive actions

  • Upgrade Siemens SIMATIC CN 4100 to V5.0 or later, per the vendor remediation guidance.
  • Confirm which deployed systems run SIMATIC CN 4100 versions earlier than 5.0 and document exposure.
  • Plan and test the update in a controlled maintenance window appropriate for industrial-control environments.
  • Use CISA-recommended ICS defense-in-depth practices to reduce blast radius while remediation is scheduled.
  • Watch for application crashes or abnormal behavior associated with XSLT processing and libxslt usage in affected systems.

Evidence notes

Source evidence comes from the CISA CSAF advisory ICSA-26-134-10, which republishes Siemens ProductCERT SSA-032379. The supplied revision history shows initial publication on 2026-05-12 and CISA republication on 2026-05-14. The advisory text, product scope, CVSS vector, and remediation all come from the provided corpus; no KEV listing was supplied.

Sources and references

Verified primary and authoritative sources

  • CVE-2025-7425 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2025-7425

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

  • CVE-2025-7425 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2025-7425

    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-26-134-10.json

    cisa_csaf

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/csaf/ssa-032379.json

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/html/ssa-032379.html

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/news-events/ics-advisories/icsa-26-134-10

    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.