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CVE-2025-38393 Siemens CVE debrief

CVE-2025-38393 is a race-condition issue in the Linux kernel’s NFSv4/pNFS path that can leave tasks stuck waiting for layout drain and writeback progress. In Siemens’ advisory for the SIMATIC S7-1500 CPU family, the impact is framed as an availability problem affecting the Linux-based subsystem, with mitigations provided and no fix available at the time of publication.

Vendor
Siemens
Product
SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)
CVSS
MEDIUM 4.7
CISA KEV
Not listed in stored evidence
Original CVE published
2025-06-10
Original CVE updated
2026-05-14
Advisory published
2025-06-10
Advisory updated
2026-05-14

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.

Sources and references

Verified primary and authoritative sources

  • CVE-2025-38393 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2025-38393

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2025-38393 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2025-38393

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • Source item URL

    Unverified legacy reference

    URL: https://raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/OT/white/2025/icsa-25-162-05.json

    cisa_csaf

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/csaf/ssa-082556.json

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/html/ssa-082556.html

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/news-events/ics-advisories/icsa-25-162-05

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/news-events/ics-alerts/ics-alert-10-301-01

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/resources-tools/resources/ics-recommended-practices

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/topics/industrial-control-systems

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/sites/default/files/recommended_practices/NCCIC_ICS-CERT_Defense_in_Depth_2016_S508C.pdf

    Reference

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.