CVE-2025-38393 Siemens CVE debrief

Who should care

OT defenders, Siemens SIMATIC S7-1500 operators, and teams responsible for Linux-based industrial controllers or embedded GNU/Linux subsystems should review this advisory, especially if they rely on NFSv4/pNFS functionality or can access the device shell.

Technical summary

The source description says the kernel issue was resolved by fixing a race to wake on NFS_LAYOUT_DRAIN. Reported symptoms included systems hung in writeback waiting on the same page lock and a task waiting on the NFS_LAYOUT_DRAIN bit even though the pnfs_layout_hdr plh_outstanding count was zero. The advisory attributes the failure mode to a waiter/waker race similar to a prior Linux kernel synchronization fix and says the remedy is to apply the advised memory barrier. The supplied CVSS vector indicates a local, high-complexity availability issue with no confidentiality or integrity impact.

Defensive priority

Medium. The score and advisory context indicate an availability-focused issue rather than code execution or data exposure, but the affected products are industrial control devices where hangs can still matter operationally.

Recommended defensive actions

• Review Siemens advisory SSA-082556 and CISA advisory ICSA-25-162-05 for the affected SIMATIC S7-1500 CPU models listed in the source.
• Apply Siemens-provided mitigations for the affected products, including restricting access to the interactive shell of the additional GNU/Linux subsystem to trusted personnel only.
• Only build and run applications from trusted sources on affected devices.
• Monitor affected systems for unexpected writeback stalls, NFS-related hangs, or broader availability degradation.
• Track the Siemens and CISA advisories for any future fix availability or updated remediation guidance.

Evidence notes

The source corpus identifies CVE-2025-38393 as a Linux kernel NFSv4/pNFS race condition and provides the exact advisory context from CISA CSAF for Siemens SIMATIC S7-1500 CPU family products. It also states that no fix is currently available and lists mitigations. The publication date used here is the supplied CVE/advisory publication date of 2025-06-10, with the latest supplied source update on 2026-05-14. No unsupported exploitability, attack path, or product behavior beyond the advisory text is added.

Official resources