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PatchSiren cyber security CVE debrief

CVE-2024-12243 Siemens CVE debrief

CVE-2024-12243 is a denial-of-service issue tracked in Siemens' SIMATIC S7-1500 CPU family advisory. The flaw is described as inefficient ASN.1/DER certificate processing in the GnuTLS/libtasn1 path, which can consume excessive resources when handling specially crafted certificate data. Siemens and CISA identify affected SIMATIC S7-1500 CPU variants and note that no fix was available in the advisory, so exposure management and source-trust controls are the practical near-term defenses.

Vendor
Siemens
Product
SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)
CVSS
MEDIUM 5.3
CISA KEV
Not listed in stored evidence
Original CVE published
2025-06-10
Original CVE updated
2026-05-14
Advisory published
2025-06-10
Advisory updated
2026-05-14

Who should care

Operators and maintainers of the affected Siemens SIMATIC S7-1500 CPU variants, especially environments using the additional GNU/Linux subsystem or applications that process untrusted certificates. OT teams that rely on these controllers for availability should treat this as a service-impacting issue.

Technical summary

The advisory links CVE-2024-12243 to GnuTLS reliance on libtasn1 for ASN.1 data processing. An inefficient algorithm can make decoding certain DER-encoded certificate data take excessive time, increasing resource consumption and potentially making the system slow or unresponsive. The CVSS vector supplied by the advisory is network-reachable with no privileges or user interaction required and with low availability impact (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L). CISA’s CSAF entry lists five affected Siemens product IDs and states that no fix is currently available.

Defensive priority

High for availability-sensitive OT deployments. While the CVSS score is medium, the practical risk is controller slowdown or unresponsiveness on affected product variants, which can disrupt operations even without direct confidentiality or integrity impact.

Recommended defensive actions

  • Identify whether any listed SIMATIC S7-1500 CPU variants are deployed in your environment.
  • Restrict access to the interactive shell of the additional GNU/Linux subsystem to trusted personnel only, as recommended in the advisory.
  • Only build and run applications from trusted sources on affected systems.
  • Monitor for unusually high CPU or resource consumption around certificate handling or TLS-related activity.
  • Track Siemens ProductCERT / CISA updates for the availability of a corrective fix and plan remediation when one is released.

Evidence notes

This debrief is based on the CISA CSAF advisory ICSA-25-162-05 (published 2025-06-10, latest republication update 2026-05-14), Siemens ProductCERT advisory SSA-082556, and the CVE record references supplied in the corpus. The advisory explicitly says no fix is currently available and provides mitigation guidance for the affected SIMATIC S7-1500 CPU product variants. No KEV listing was provided in the source corpus.

Sources and references

Verified primary and authoritative sources

  • CVE-2024-12243 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2024-12243

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

  • CVE-2024-12243 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2024-12243

    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-25-162-05.json

    cisa_csaf

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/csaf/ssa-082556.json

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/html/ssa-082556.html

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/news-events/ics-advisories/icsa-25-162-05

    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.