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PatchSiren cyber security CVE debrief

CVE-2025-40801 Siemens CVE debrief

CVE-2025-40801 affects Siemens COMOS and is caused by the SALT SDK not validating the server certificate when establishing TLS connections to the authorization server. In the supplied advisory data, that weakness could allow a man-in-the-middle attack against affected connections. Siemens recommends updating to V10.6.1 or later.

Vendor
Siemens
Product
COMOS V10.4
CVSS
CRITICAL 9.2
CISA KEV
Not listed in stored evidence
Original CVE published
2025-12-09
Original CVE updated
2026-09-30
Advisory published
2025-12-09
Advisory updated
2026-09-30

Who should care

Organizations running Siemens COMOS versions listed in the advisory, especially administrators and defenders responsible for authentication infrastructure, application connectivity, and patch management.

Technical summary

The issue is a TLS trust failure: the client-side SALT SDK does not properly validate the authorization server certificate during TLS setup. That means a network-positioned attacker may be able to intercept or alter the connection. The supplied CVSS vector is CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H, indicating network reachability, no required privileges, and high potential impact.

Defensive priority

High. The flaw is network-reachable and can affect confidentiality, integrity, and availability, even though the attack complexity is rated high and the issue is not marked as KEV in the supplied data.

Recommended defensive actions

  • Upgrade Siemens COMOS to V10.6.1 or later, per the supplied remediation.
  • Review the Siemens and CISA advisory pages for version-specific fix guidance before scheduling maintenance.
  • Verify whether any affected COMOS installations are using the vulnerable SALT SDK connection path to the authorization server.
  • Prioritize patching exposed or externally reachable management and integration environments first.
  • Apply defense-in-depth controls for industrial/OT environments, including segmented networks and monitoring for anomalous TLS or authorization traffic.

Evidence notes

The supplied CISA CSAF advisory ICSA-26-043-03 for Siemens COMOS states that the SALT SDK is missing server certificate validation while establishing TLS connections to the authorization server, which could allow a man-in-the-middle attack. The advisory was published on 2025-12-09 and later republished/updated, with the latest supplied modification timestamp of 2026-03-12. The remediation field specifies update to V10.6.1 or later. The supplied product/version data lists COMOS V10.4, V10.4.5, V10.5, and V10.6.

Sources and references

Verified primary and authoritative sources

  • CVE-2025-40801 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2025-40801

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

  • CVE-2025-40801 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2025-40801

    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-26-043-03.json

    cisa_csaf

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/csaf/ssa-212953.json

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/html/ssa-212953.html

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/news-events/ics-advisories/icsa-26-043-03

    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.