CVE-2025-38552 Cert Portal CVE debrief

Who should care

Operators and maintainers responsible for Siemens SIMATIC CN 4100 deployments, especially where the product is managed through the referenced Siemens/CISA advisory chain. Linux kernel and networking maintainers should also note the underlying MPTCP race condition described in the source text.

Technical summary

The supplied description says the Linux kernel MPTCP code had a race between subflow failure and additional subflow creation. The fix introduces a separate flag, protected by the fallback lock, to represent when socket state should prevent additional subflow creation. The socket fallback path and MP_FAIL handling set that flag, and allow_infinite_fallback is now always accessed under the relevant lock so the write-side ONCE annotation can be removed.

Defensive priority

Medium. The CVSS vector provided is CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:H, indicating local attack conditions with high complexity and potential availability impact. Prioritize according to exposure of affected Siemens assets and the applicability of the referenced vendor fix.

Recommended defensive actions

• Review the Siemens ProductCERT/CISA advisory chain for applicability to your installed SIMATIC CN 4100 versions.
• Update affected systems to V5.0 or later, per the supplied remediation guidance.
• Validate whether any deployed assets match the affected product/version range before maintenance.
• Apply the update using standard OT change-control and maintenance procedures.
• Track the source mismatch in your internal ticketing or asset management process so the product-to-CVE mapping is verified before broad rollout.

Evidence notes

Source metadata states publication on 2026-05-12 and modification on 2026-05-14, with CISA revision history showing initial publication and a republication from Siemens ProductCERT SSA-032379. The source advisory lists productNames including Siemens SIMATIC CN 4100 vers:intdot/<5.0, while the vulnerability description text itself is a Linux kernel MPTCP race-condition fix. The supplied CVSS vector is CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:H and severity is MEDIUM.

Official resources