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PatchSiren cyber security CVE debrief

CVE-2025-0665 Siemens CVE debrief

CVE-2025-0665 is a Siemens advisory item tied to a libcurl file-descriptor handling flaw in SINEC OS firmware and related Siemens industrial networking products. The issue can cause the same eventfd file descriptor to be closed twice during connection teardown after threaded name resolution. Siemens provides a fix in V3.3 or later, and CISA republished the advisory with later scope clarifications. Given the CVSS 7.3 network-reachable profile and low confidentiality/integrity/availability impact, this is a high-priority patch item for operational environments running affected firmware.

Vendor
Siemens
Product
RUGGEDCOM RST2428P (6GK6242-6PA00)
CVSS
HIGH 7.3
CISA KEV
Not listed in stored evidence
Original CVE published
2026-01-28
Original CVE updated
2026-02-25
Advisory published
2026-01-28
Advisory updated
2026-02-25

Who should care

Siemens OT/ICS administrators, industrial network engineers, asset owners of affected RUGGEDCOM and SCALANCE devices, and security teams responsible for firmware lifecycle management.

Technical summary

The source advisory describes a libcurl bug where a connection channel teardown can wrongly close the same eventfd file descriptor twice after a threaded name resolve completes. CISA’s CSAF record ties the issue to Siemens SINEC OS firmware and lists multiple affected Siemens product families. The supplied CVSS vector is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L, indicating a network-reachable issue with limited but real impact.

Defensive priority

High

Recommended defensive actions

  • Update affected Siemens devices to V3.3 or later, per Siemens remediation guidance.
  • Confirm which deployed models and firmware revisions are actually in scope, since CISA later clarified and expanded the affected-product listing.
  • Prioritize patching of exposed or operationally critical assets during planned maintenance windows.
  • After remediation, verify firmware version and validate normal service behavior on each updated device.
  • Apply industrial-control-system network segmentation and minimize management-plane exposure, following CISA ICS recommended practices.
  • Monitor Siemens and CISA advisories for any additional scope or remediation updates.

Evidence notes

The source corpus consistently describes the flaw as libcurl incorrectly closing the same eventfd file descriptor twice after threaded name resolution. Siemens remediation guidance in the advisory points to updating to V3.3 or later. The CISA CSAF revision history shows publication on 2026-01-28, a 2026-02-24 scope clarification, and a 2026-02-25 republication update based on Siemens ProductCERT advisory SSA-089022.

Sources and references

Verified primary and authoritative sources

  • CVE-2025-0665 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2025-0665

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

  • CVE-2025-0665 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2025-0665

    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-26-043-06.json

    cisa_csaf

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/csaf/ssa-089022.json

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/html/ssa-089022.html

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/news-events/ics-advisories/icsa-26-043-06

    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.