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PatchSiren cyber security CVE debrief

CVE-2025-38681 Cert Portal CVE debrief

CVE-2025-38681 is a race condition in Linux kernel ptdump page-table inspection paths. During memory hot-remove, kernel page tables can change while ptdump_walk_pgd() or ptdump_check_wx() is reading them. In the worst case, freed intermediate page-table memory can be reused, letting the dump code dereference stale pointers and potentially crash or otherwise misbehave. The provided advisory data ties the issue to a Siemens SIMATIC CN 4100 record, but that product association is low-confidence and should be verified against the linked vendor advisory.

Vendor
Cert Portal
Product
Siemens SIMATIC CN 4100 vers:intdot/<5.0
CVSS
MEDIUM 6.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-05-12
Original CVE updated
2026-05-14
Advisory published
2026-05-12
Advisory updated
2026-05-14

Who should care

Linux kernel maintainers, OT/ICS administrators, and platform teams responsible for systems that expose kernel page-table debug interfaces or include the affected ptdump paths. Treat the Siemens SIMATIC CN 4100 product mapping as needing verification.

Technical summary

The source advisory describes a race between kernel page-table dumping and concurrent memory hotplug teardown. Leaf-entry changes can produce stale output, but freeing intermediate page-table levels creates a use-after-free risk inside the ptdump traversal. The fix moves the memory hotplug lock into the generic ptdump path so both kernel_page_tables and check_wx_pages use consistent synchronization. The supplied CVSS vector is CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:H (6.5, Medium).

Defensive priority

Medium

Recommended defensive actions

  • Apply the vendor-fixed release identified in the source advisory: update to V5.0 or later.
  • Verify whether your environment actually uses the affected Siemens mapping or the underlying Linux kernel ptdump code, since the source record’s product association is low-confidence.
  • Prioritize systems where local users can access kernel debugfs or page-table inspection interfaces.
  • Review kernel update cadence for OT/ICS appliances and Linux-based embedded devices that inherit the affected kernel code.
  • Confirm the fix by checking the linked Siemens ProductCERT and CISA advisory records for the final affected-version matrix.

Evidence notes

The supplied CISA CSAF source (ICSA-26-134-10) was published on 2026-05-12 and republished on 2026-05-14. Its description explains the race in mm/ptdump and the synchronization change that moves the memory hotplug lock into the generic ptdump path. The source record also maps the CVE to Siemens SIMATIC CN 4100 vers:intdot/<5.0, but that mapping is marked low-confidence in the prompt and should be verified against the linked vendor advisory. No KEV entry is provided in the supplied enrichment.

Official resources

Publicly disclosed in CISA ICS advisory ICSA-26-134-10 on 2026-05-12, with a CISA republication on 2026-05-14 incorporating Siemens ProductCERT advisory SSA-032379. The supplied enrichment does not list this CVE in CISA KEV.