PatchSiren cyber security CVE debrief

CVE-2024-35940 Siemens CVE debrief

A null pointer dereference vulnerability exists in the Linux kernel's pstore/zone subsystem within the psz_kmsg_read function. The flaw occurs when the function fails to validate a pointer before dereferencing it, potentially leading to a kernel crash and denial of service. This affects the GNU/Linux subsystem of Siemens SIMATIC S7-1500 TM MFP industrial control devices. The vulnerability requires local access with low privileges and no user interaction, making it exploitable by authenticated users with shell access to the GNU/Linux subsystem. The CVSS 3.1 score of 5.5 reflects medium severity with high availability impact but no confidentiality or integrity impact.

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: 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; OT security teams managing embedded Linux environments; asset owners requiring high availability for manufacturing or process control systems

Technical summary

The vulnerability exists in fs/pstore/zone.c in the Linux kernel's persistent storage (pstore) zone implementation. The psz_kmsg_read function lacks a null pointer check before dereferencing a pointer, which can trigger a kernel oops or panic when reading from the pstore zone. This is classified as CWE-476 (NULL Pointer Dereference). The attack vector is local, requiring low privileges and no user interaction. The vulnerability specifically impacts availability with no direct confidentiality or integrity effects. Siemens has confirmed no fix is currently available as of the advisory publication.

Defensive priority

medium

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 crashes or kernel panics on affected devices
Apply vendor security updates when Siemens releases a fix for this vulnerability
Implement network segmentation to limit access to industrial control devices
Review and apply CISA ICS recommended practices for defense-in-depth strategies

Evidence notes

CVE published 2024-04-09 per official CVE record. CISA ICS advisory ICSA-24-102-01 published same date. Advisory last modified 2026-05-14 with multiple revision updates adding additional CVEs to the same Siemens product advisory. Source corpus indicates this vulnerability is tracked under CWE-476 (NULL Pointer Dereference).

Official resources

2024-04-09