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CVE-2024-40993 Siemens CVE debrief

A vulnerability in the Linux kernel's netfilter ipset subsystem involves improper use of rcu_dereference_protected(), which can lead to memory corruption or use-after-free conditions. The issue stems from incorrect RCU (Read-Copy-Update) synchronization primitives in the ipset code path. This affects Siemens SIMATIC S7-1500 TM MFP industrial control systems that utilize the GNU/Linux subsystem for extended functionality. The vulnerability requires local access to exploit, with low attack complexity and low privileges needed, but can result in complete confidentiality, integrity, and availability compromise of the affected system.

Vendor
Siemens
Product
SIMATIC S7-1500 TM MFP - GNU/Linux subsystem
CVSS
HIGH 7.8
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 control system operators using Siemens SIMATIC S7-1500 TM MFP with the GNU/Linux subsystem enabled; security teams responsible for OT/ICS environments; network administrators managing segmented industrial networks; compliance officers tracking CVE coverage for critical infrastructure assets.

Technical summary

The vulnerability exists in the Linux kernel's netfilter ipset subsystem where rcu_dereference_protected() is used suspiciously, indicating potential RCU synchronization issues. This can lead to race conditions, memory corruption, or use-after-free vulnerabilities when handling ipset operations. The affected product is the GNU/Linux subsystem within Siemens SIMATIC S7-1500 TM MFP industrial controllers, which provides extended computing capabilities beyond standard PLC functions.

Defensive priority

HIGH

Recommended defensive actions

  • Restrict interactive shell access to the GNU/Linux subsystem to trusted personnel only
  • Build and run applications only from trusted sources
  • Monitor for anomalous process behavior or unexpected kernel panics on affected devices
  • Apply vendor patches when Siemens releases a fix for this vulnerability
  • Implement network segmentation to limit exposure of industrial control systems
  • Review and apply CISA ICS recommended practices for defense in depth

Evidence notes

The vulnerability description indicates suspicious rcu_dereference_protected() usage in netfilter ipset, which is a kernel-level networking component. The CVSS 3.1 vector (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H) confirms local attack vector with high impact potential. Siemens has acknowledged this vulnerability affects the GNU/Linux subsystem of SIMATIC S7-1500 TM MFP devices.

Official resources

CVE-2024-40993 was published on 2024-04-09 and last modified on 2026-05-14. The vulnerability was disclosed through CISA's ICS advisory ICSA-24-102-01, which has undergone multiple revisions adding additional CVEs through September 2025.