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CVE-2025-40935 Siemens CVE debrief

CVE-2025-40935 is a Siemens RUGGEDCOM vulnerability in the web service TLS certificate upload process. Because the device does not properly validate input, an authenticated remote attacker can trigger a crash and reboot, resulting in a temporary denial of service. Siemens and CISA list remediations in V5.10.1 or later for affected RUGGEDCOM V5.X models.

Vendor
Siemens
Product
RUGGEDCOM RMC8388 V5.X
CVSS
MEDIUM 5.3
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

Industrial network operators, OT administrators, and Siemens RUGGEDCOM defenders who manage affected V5.X devices—especially where the web service is reachable and certificate uploads are part of normal administration.

Technical summary

The flaw is an input validation failure during TLS certificate upload in the web service. The supplied CVSS vector is CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L, indicating network reachability, low attack complexity, required low privileges, no user interaction, and availability-only impact. The documented effect is a device crash and reboot that creates a temporary denial of service.

Defensive priority

Medium priority. Patch promptly if affected devices are in production, exposed to remote administration, or used in critical availability-dependent environments.

Recommended defensive actions

  • Update affected devices to V5.10.1 or later, as recommended by Siemens.
  • Restrict access to the web service to trusted administrative networks and accounts only.
  • Review who can upload TLS certificates and remove unnecessary administrative privileges.
  • Monitor affected devices for unexpected reboots or certificate upload activity.
  • Follow CISA and Siemens industrial control system defense-in-depth guidance for segmentation, access control, and monitoring.

Evidence notes

This debrief is based on the supplied CISA CSAF source item ICSA-26-015-05 and Siemens ProductCERT advisory SSA-763474 referenced therein. The source description states that affected devices do not properly validate input during TLS certificate upload, enabling an authenticated remote attacker to trigger a crash and reboot. The advisory was published on 2025-12-09 and republished/updated on 2026-01-14 with Siemens ProductCERT material. Remediation in the source is V5.10.1 or later.

Sources and references

Verified primary and authoritative sources

  • CVE-2025-40935 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2025-40935

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

  • CVE-2025-40935 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2025-40935

    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-26-015-05.json

    cisa_csaf

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/csaf/ssa-763474.json

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/html/ssa-763474.html

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/news-events/ics-advisories/icsa-26-015-05

    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.