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CVE-2024-36899 Siemens CVE debrief

A use-after-free vulnerability in the Linux kernel's GPIO character device subsystem affects Siemens SIMATIC S7-1500 TM MFP industrial controllers. The flaw occurs in the gpiolib cdev implementation when gpio_chrdev_release() frees the watched_lines bitmap while a concurrent line release operation holds the notifier chain's read-write semaphore, creating a race condition that can lead to memory corruption. This HIGH severity vulnerability (CVSS 7.0) requires local access with low privileges and has high attack complexity. The affected product is the GNU/Linux subsystem within Siemens SIMATIC S7-1500 TM MFP programmable logic controllers used in industrial automation environments. No patch is currently available; mitigation relies on restricting interactive shell access to trusted personnel and running only trusted applications.

Vendor
Siemens
Product
SIMATIC S7-1500 TM MFP - GNU/Linux subsystem
CVSS
HIGH 7
CISA KEV
Not listed in stored evidence
Original CVE published
2024-04-09
Original CVE updated
2026-05-14
Advisory published
2024-04-09
Advisory updated
2026-05-14

Who should care

Industrial automation engineers, OT security teams, critical infrastructure operators using Siemens SIMATIC S7-1500 TM MFP controllers, and organizations with embedded Linux systems utilizing gpiolib character devices

Technical summary

The vulnerability exists in drivers/gpio/gpiolib-cdev.c where gpio_chrdev_release() calls bitmap_free() on watched_lines, but lineinfo_changed_nb notifier unregistration may fail when blocked on a write rwsem. Concurrently, a GPIO line release holds the read rwsem, creating a race where watched_lines is accessed after free. This is CWE-416 (Use After Free) affecting kernel versions prior to the fix. The GNU/Linux subsystem on SIMATIC S7-1500 TM MFP exposes this attack surface through its GPIO character device interface.

Defensive priority

HIGH

Recommended defensive actions

  • Restrict interactive shell access to the GNU/Linux subsystem to trusted personnel only
  • Execute only applications from trusted sources on affected systems
  • Monitor for anomalous process behavior or unexpected GPIO subsystem activity
  • Apply vendor patches when released by Siemens
  • Review and implement CISA ICS recommended practices for defense-in-depth
  • Segment industrial control networks to limit lateral movement opportunities

Evidence notes

Vulnerability description and affected product confirmed through CISA ICS advisory ICSA-24-102-01 and Siemens security advisory SSA-265688. CVSS vector AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H indicates local attack vector with high complexity but complete impact to confidentiality, integrity, and availability. The use-after-free specifically involves watched_lines bitmap accessed after gpio_chrdev_release() in gpiolib cdev lineinfo_changed_notify.

Sources and references

Verified primary and authoritative sources

  • CVE-2024-36899 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2024-36899

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

  • CVE-2024-36899 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2024-36899

    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.