PatchSiren cyber security CVE debrief

CVE-2023-52882 Siemens CVE debrief

This CVE addresses a Linux kernel clock driver instability in the Allwinner H6 SoC's sunxi-ng clock framework. The vulnerability occurs when the PLL CPUX clock rate changes while the CPU is actively running from that clock source. Under these conditions, intermittent system instability manifests as crashes and undefined behavior. The root cause stems from insufficient clock source stability during dynamic frequency scaling operations. The implemented fix reparents the CPUX clock to a stable 24 MHz oscillator during PLL CPUX rate transitions, eliminating the race condition between clock domain switching and CPU execution. This vulnerability affects Siemens industrial networking products running SINEC OS that incorporate the vulnerable Linux kernel components. The vendor has released updates to address this issue.

Vendor: Siemens
Product: RUGGEDCOM RST2428P (6GK6242-6PA00)
CVSS: NONE
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

Organizations operating Siemens industrial networking infrastructure including SCALANCE XC-300/XR-300/XC-400/XR-500WG/XR-500 family switches, SCALANCE XCM-/XRM-/XCH-/XRH-300 family devices, and RUGGEDCOM RST2428P platforms. System integrators deploying Allwinner H6-based embedded systems in critical infrastructure applications. OT security teams responsible for patch management in manufacturing, energy, and transportation environments where these devices provide network backbone connectivity.

Technical summary

The vulnerability exists in the clk/sunxi-ng/h6.c Linux kernel driver managing clock domains for the Allwinner H6 system-on-chip. During dynamic voltage and frequency scaling (DVFS) operations, the PLL CPUX clock undergoes rate changes while the CPU continues executing instructions from that same clock domain. This creates a metastability window where clock glitches or phase discontinuities can corrupt processor state. The resolution implements temporary clock reparenting: before modifying PLL CPUX parameters, the driver switches the CPUX clock source to the always-stable 24 MHz oscillator, executes the PLL reconfiguration, then restores the CPUX source to the newly-stabilized PLL output. This pattern eliminates the vulnerable overlap between clock configuration changes and active CPU execution.

Defensive priority

medium

Recommended defensive actions

Apply vendor-provided firmware updates to V3.1 or later for affected Siemens SCALANCE and RUGGEDCOM products
Verify current SINEC OS version through device management interface before scheduling maintenance windows
Test frequency scaling operations in non-production environments after patch deployment to confirm stability
Monitor system logs for clock-related warnings or unexpected resets on H6-based systems prior to patching
Review network segmentation for affected industrial control devices to limit exposure during patching windows

Evidence notes

The vulnerability description indicates extensive testing (30+ hours with frequent frequency switches) validated the fix's effectiveness. The source advisory underwent multiple revisions between initial publication and final republication, with the most recent update on 2026-02-25 reflecting synchronization with Siemens ProductCERT advisory SSA-613116. The CVSS vector provided in source references (AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:N) suggests network attack vector with high attack complexity, though the final severity assessment shows NONE.

Official resources

2025-08-12