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CVE-2023-0045 Siemens CVE debrief

CVE-2023-0045 is a medium-severity issue described in Siemens’ ICS advisory for SCALANCE W-series products. The advisory says the Linux prctl-based mitigation for indirect branch prediction barriers (IBPB) is not issued immediately when the syscall runs; instead, the task flags are updated and IBPB is only triggered on the next schedule check. That creates a short exposure window where previously injected BTB state may still influence execution before the mitigation takes effect. Siemens lists 19 affected SCALANCE WAB/WAM/WUB/WUM variants and recommends upgrading to V3.0.0 or later.

Vendor
Siemens
Product
SCALANCE WAB762-1 (6GK5762-1AJ00-6AA0)
CVSS
MEDIUM 4.7
CISA KEV
Not listed in stored evidence
Original CVE published
2025-02-11
Original CVE updated
2025-05-06
Advisory published
2025-02-11
Advisory updated
2025-05-06

Who should care

OT/ICS administrators, network security teams, and maintenance owners responsible for Siemens SCALANCE WAB/WAM/WUB/WUM devices should care, especially where local, privileged access is possible or where the organization relies on kernel speculation mitigations for confidentiality protection.

Technical summary

Per the supplied CSAF advisory text, the issue is a timing flaw in the prctl syscall path: ib_prctl_set updates Thread Information Flags and SPEC_CTRL state via __speculation_ctrl_update, but the IBPB itself is deferred until the next scheduler pass when TIF bits are checked. The advisory explains that this delay leaves a window for BTB-injected values to remain effective before mitigation is applied. The CVSS vector provided is AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N (4.7 medium), which aligns with a locally exploitable confidentiality impact and no integrity or availability impact in the supplied record.

Defensive priority

Medium. The attack conditions are local and relatively constrained, but the confidentiality impact is high and Siemens has provided a concrete upgrade path. Treat as a targeted patching item for affected SCALANCE deployments rather than a broad emergency response.

Recommended defensive actions

  • Identify whether any deployed Siemens SCALANCE WAB/WAM/WUB/WUM models match the 19 affected product names in the advisory.
  • Review the installed firmware/software version and compare it to Siemens’ remediation guidance.
  • Apply Siemens’ recommended update to V3.0.0 or later for affected products.
  • Schedule maintenance to minimize operational disruption during the update window.
  • Track the Siemens security advisory and CISA CSAF record for any follow-up revisions or clarifications.

Evidence notes

The source CSAF advisory (CISA-hosted ICSA-25-044-09) ties CVE-2023-0045 to Siemens SCALANCE W-series products and states that the prctl-based IBPB mitigation is delayed until the next schedule check. The advisory lists 19 affected product variants and gives the remediation 'Update to V3.0.0 or later version.' The supplied timeline shows first publication on 2025-02-11 and a later revision on 2025-05-06 for typo fixes. This debrief uses only the supplied advisory text and official reference links; it does not assume exploit details beyond the record.

Official resources

Published by CISA on 2025-02-11 and revised on 2025-05-06 for typo fixes. The underlying issue description in the supplied advisory is sourced to Siemens’ security notice for affected SCALANCE products.