PatchSiren cyber security CVE debrief

CVE-2024-26934 Siemens CVE debrief

A deadlock vulnerability in the Linux kernel's USB core subsystem affects Siemens SIMATIC S7-1500 TM MFP industrial control systems. The flaw resides in usb_deauthorize_interface(), where improper locking can cause the kernel to hang, resulting in denial of service. With local access and low privileges, an attacker can trigger this deadlock, potentially impacting availability of critical industrial processes. The vulnerability was disclosed in April 2024 and remains unpatched as of the latest advisory update in September 2025.

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, OT security teams, and organizations deploying Siemens SIMATIC S7-1500 TM MFP controllers in manufacturing, process control, or critical infrastructure environments. System integrators and maintenance personnel with access to the GNU/Linux subsystem should be aware of this unpatched vulnerability.

Technical summary

The vulnerability exists in the usb_deauthorize_interface() function within the Linux kernel USB core. A deadlock condition can occur due to improper locking semantics when deauthorizing USB interfaces. This is classified under CWE-667 (Improper Locking). The flaw requires local access with low privileges to exploit, but results in high impact across confidentiality, integrity, and availability dimensions. The affected product is the GNU/Linux subsystem embedded in Siemens SIMATIC S7-1500 TM MFP programmable logic controllers used in industrial automation environments. No patch is currently available; mitigation relies on access controls and trusted application execution.

Defensive priority

HIGH

Recommended defensive actions

Restrict interactive shell access to the GNU/Linux subsystem to trusted personnel only
Implement application whitelisting to ensure only trusted applications are built and executed
Monitor for anomalous USB device authorization attempts on affected systems
Apply defense-in-depth strategies per CISA ICS recommended practices pending vendor patch availability

Evidence notes

CISA ICS advisory ICSA-24-102-01 documents this vulnerability in the GNU/Linux subsystem of Siemens SIMATIC S7-1500 TM MFP. The advisory explicitly states 'Currently no fix is available' as of its September 9, 2025 update. 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 on confidentiality, integrity, and availability.

Official resources

2024-04-09