CVE-2023-23454 Siemens CVE debrief

Who should care

Siemens SCALANCE WAB/WAM/WUB/WUM product owners, OT network administrators, and patching teams responsible for the listed 762/763/766-1 devices should prioritize this advisory, especially where device availability is operationally important.

Technical summary

The vulnerability is described as a type confusion in net/sched/sch_cbq.c's cbq_classify logic in the Linux kernel through 6.1.4. The bug can cause a slab-out-of-bounds read and denial of service when a non-negative value is treated as a valid classification result even though it may represent TC_ACT_SHOT. The supplied Siemens CSAF advisory ties this kernel issue to 19 SCALANCE product variants and provides a fixed target of V3.0.0 or later.

Defensive priority

Medium overall by CVSS, but operationally important in OT deployments because the impact is availability loss on affected network devices. Prioritize patching on exposed or business-critical SCALANCE systems.

Recommended defensive actions

• Update affected Siemens SCALANCE products to V3.0.0 or later, per the Siemens remediation guidance.
• Inventory the listed SCALANCE WAB/WAM/WUB/WUM 762/763/766-1 variants to confirm whether any affected models are deployed.
• Plan maintenance windows and validate the update path before deployment, especially for production OT environments.
• Restrict local access to affected systems and administrative interfaces where practical until remediation is completed.
• Use the Siemens and CISA advisory references to verify exact product coverage and remediation scope before making changes.

Evidence notes

The CVE description supplied here states the Linux kernel issue, the cbq_classify function, the slab-out-of-bounds read outcome, and the type-confusion mechanism. The CISA CSAF source item (ICSA-25-044-09) lists 19 affected Siemens SCALANCE product variants, the publication date of 2025-02-11, the revision on 2025-05-06 for typo fixes, and the remediation instruction to update to V3.0.0 or later. No KEV listing was included in the supplied data.

Official resources