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PatchSiren cyber security CVE debrief

CVE-2025-40818 Siemens CVE debrief

Siemens SINEMA Remote Connect Server contains private SSL/TLS keys that are not properly protected on the server. An authenticated user with server access may be able to read those keys and potentially impersonate the server, enabling man-in-the-middle attacks, traffic decryption, or unauthorized access to services that trust the affected certificates. CISA classifies the issue as low severity and the supplied CVSS vector indicates local, low-privilege access is required. Siemens provides a fixed release in V3.2 SP4 or later.

Vendor
Siemens
Product
SINEMA Remote Connect Server
CVSS
LOW 3.3
CISA KEV
Not listed in stored evidence
Original CVE published
2025-12-09
Original CVE updated
2025-12-09
Advisory published
2025-12-09
Advisory updated
2025-12-09

Who should care

Organizations running Siemens SINEMA Remote Connect Server, especially environments where local or authenticated server users exist and where certificate trust is relied on for remote connectivity or service authentication.

Technical summary

The advisory describes a server-side key protection weakness rather than a flaw in TLS protocol design. Private key material is stored with insufficient access protection, so a user with access to the server can read the keys. If the affected keys are obtained, an attacker could present the server identity using trusted certificates and potentially intercept or decrypt traffic. The supplied CVSS v3.1 vector is AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N, reflecting local access requirements and confidentiality impact.

Defensive priority

Medium: patch promptly, because exposed private keys can undermine trust relationships even though the attack requires server access and the published CVSS score is low.

Recommended defensive actions

  • Update Siemens SINEMA Remote Connect Server to V3.2 SP4 or later.
  • Review filesystem and service permissions protecting TLS private key material on affected servers.
  • Restrict and monitor local/authenticated server access, including administrative accounts and service users.
  • If key exposure is suspected, rotate the affected certificates and private keys and validate downstream trust dependencies.
  • Check logs and host access records for unauthorized access to key stores or certificate files.

Evidence notes

This debrief is based on the CISA CSAF advisory ICSA-25-345-06 for CVE-2025-40818 and the linked Siemens advisory SSA-626856. The supplied advisory text states that private SSL/TLS keys on the server are not properly protected and may be read by any user with server access. The remediation field specifies updating to V3.2 SP4 or later. The supplied CVSS vector is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N, and no CISA KEV entry was provided.

Sources and references

Verified primary and authoritative sources

  • CVE-2025-40818 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2025-40818

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

  • CVE-2025-40818 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2025-40818

    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/2025/icsa-25-345-06.json

    cisa_csaf

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/csaf/ssa-626856.json

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/html/ssa-626856.html

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/news-events/ics-advisories/icsa-25-345-06

    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.