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CVE-2025-49794 Siemens CVE debrief

CVE-2025-49794 is a critical use-after-free in libxml2 affecting Siemens RUGGEDCOM ROX products covered by the CISA/Siemens advisory. The issue can be triggered during XPath parsing when Schematron uses <sch:name path="..."/> elements, allowing crafted XML input to crash the program and potentially cause other undefined behavior. Siemens lists affected RUGGEDCOM ROX models and recommends updating to V2.17.1 or later.

Vendor
Siemens
Product
RUGGEDCOM ROX MX5000
CVSS
CRITICAL 9.1
CISA KEV
Not listed in stored evidence
Original CVE published
2025-06-16
Original CVE updated
2026-09-28
Advisory published
2025-06-16
Advisory updated
2026-09-28

Who should care

OT/ICS operators and engineers managing Siemens RUGGEDCOM ROX devices, plus teams that process untrusted XML through libxml2-based workflows. Priority is highest where these devices or parsing pipelines are exposed to external or semi-trusted XML content.

Technical summary

The advisory describes a use-after-free in libxml2 that occurs under specific XPath/Schematron parsing conditions involving <sch:name path="..."/> schema elements. According to the supplied CVSS vector (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H), no privileges or user interaction are required, and the likely impact is high integrity and availability loss, with crash and undefined behavior explicitly called out in the description. The source advisory ties the issue to Siemens RUGGEDCOM ROX products and recommends upgrading to V2.17.1 or later.

Defensive priority

Immediate. Treat as a critical patching item for affected Siemens RUGGEDCOM ROX assets and any deployment that ingests untrusted XML/Schematron content.

Recommended defensive actions

  • Upgrade affected Siemens RUGGEDCOM ROX devices to V2.17.1 or later, per the advisory.
  • Inventory all ROX models listed in the advisory and confirm which versions are deployed.
  • Identify any workflows that accept external XML, XPath, or Schematron input and restrict exposure where possible.
  • Apply compensating controls to limit access to XML-processing services and management interfaces until patched.
  • Test updates in a maintenance window appropriate for OT environments and verify vendor guidance before rollout.
  • Monitor for crashes or abnormal behavior in systems that parse XML with libxml2.

Evidence notes

Supplied source data identifies CISA advisory ICSA-26-134-16, republished from Siemens ProductCERT SSA-577017, with publication on 2026-05-12 UTC and a republication/update on 2026-05-14 UTC. The advisory description states a libxml2 use-after-free during XPath parsing when Schematron includes <sch:name path="..."/> elements, and lists Siemens RUGGEDCOM ROX products with remediation to V2.17.1 or later. The supplied enrichment marks this as not KEV-listed.

Sources and references

Verified primary and authoritative sources

  • CVE-2025-49794 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2025-49794

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

  • CVE-2025-49794 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2025-49794

    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-26-134-16.json

    cisa_csaf

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/csaf/ssa-577017.json

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/html/ssa-577017.html

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/news-events/ics-advisories/icsa-26-134-16

    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.