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CVE-2024-36974 Siemens CVE debrief

CVE-2024-36974 is a medium-severity vulnerability (CVSS 5.5) in the Linux kernel's taprio network scheduler, affecting the Siemens SIMATIC S7-1500 TM MFP GNU/Linux subsystem. The flaw exists in the `taprio_parse_mqprio_opt()` function within `net/sched/taprio.c`, where improper validation of the `TCA_TAPRIO_ATTR_PRIOMAP` attribute allows userspace to inject arbitrary data into the kernel on subsequent calls to `taprio_change()`. The vulnerability stems from a state-dependent validation bypass: an initial call with valid attributes sets `dev->num_tc` to a non-zero value, causing a second call with malicious mqprio attributes to return early from validation without proper checks, potentially leading to denial of service conditions. Published on April 9, 2024, and last modified on May 14, 2026, this vulnerability is not listed in CISA's Known Exploited Vulnerabilities catalog. Siemens has not released a patch as of the advisory date; mitigations focus on restricting access to the GNU/Linux subsystem's interactive shell to trusted personnel only and ensuring only applications from trusted sources are built and executed.

Vendor
Siemens
Product
SIMATIC S7-1500 TM MFP - GNU/Linux subsystem
CVSS
MEDIUM 5.5
CISA KEV
Not listed in stored evidence
Original CVE published
2025-08-12
Original CVE updated
2026-02-25
Advisory published
2025-08-12
Advisory updated
2026-02-25

Who should care

Industrial control system operators, OT security engineers, and asset owners deploying Siemens SIMATIC S7-1500 TM MFP with the GNU/Linux subsystem enabled. Organizations utilizing time-sensitive networking (TSN) features with taprio scheduling should prioritize access controls until a patch is available.

Technical summary

The vulnerability resides in the taprio (Time-Aware Priority Shaper) network scheduler implementation in the Linux kernel. The `taprio_parse_mqprio_opt()` function fails to consistently validate the `TCA_TAPRIO_ATTR_PRIOMAP` attribute across multiple invocations. When `taprio_change()` is called initially with valid attributes, `dev->num_tc` is set to a non-zero value. On a subsequent call with arbitrary or malicious mqprio attributes, the function returns early from `taprio_parse_mqprio_opt()` due to the existing non-zero `dev->num_tc` state, bypassing validation and allowing injection of arbitrary data into kernel structures. This state-dependent validation flaw can result in undefined behavior and denial of service. The CVSS 3.1 vector (AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H) reflects a local attack scenario requiring low privileges with high availability impact.

Defensive priority

medium

Recommended defensive actions

  • Restrict interactive shell access to the SIMATIC S7-1500 TM MFP GNU/Linux subsystem to authorized personnel only
  • Implement application whitelisting to ensure only trusted applications are built and executed on affected systems
  • Monitor for anomalous network scheduler configuration changes or repeated taprio interface modifications
  • Apply defense-in-depth strategies per ICS-CERT recommended practices for industrial control systems
  • Subscribe to Siemens ProductCERT security advisories for patch availability notifications

Evidence notes

Vulnerability description and product impact derived from CISA CSAF advisory ICSA-24-102-01. CVSS vector AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H indicates local attack vector with low attack complexity, low privileges required, and high availability impact. No confidentiality or integrity impact per CVSS scoring.

Sources and references

Verified primary and authoritative sources

  • CVE-2024-36974 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2024-36974

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

  • CVE-2024-36974 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2024-36974

    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/2024/icsa-24-102-01.json

    cisa_csaf

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/csaf/ssa-265688.json

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/html/ssa-265688.html

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/news-events/ics-advisories/icsa-24-102-01

    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.