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PatchSiren cyber security CVE debrief

CVE-2025-40258 Siemens CVE debrief

A use-after-free vulnerability exists in the Linux kernel's mptcp_schedule_work() function. This issue arises from a race condition where a work is scheduled, and a reference count is obtained on sk->sk_refcnt if the work was scheduled. However, if mptcp_worker() runs immediately and completes before the reference count is obtained, it can lead to a use-after-free condition.

Vendor
Siemens
Product
RUGGEDCOM RST2428P (6GK6242-6PA00)
CVSS
HIGH 7.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-02
Original CVE updated
2026-07-07
Advisory published
2026-06-02
Advisory updated
2026-07-07

Who should care

Linux kernel maintainers, Linux distribution maintainers, and users of Linux-based systems, especially those utilizing the MPTCP protocol, should assess exposure and prioritize verification of affected systems.

Why it matters

CVE-2025-40258 is a use-after-free vulnerability in the Linux kernel's mptcp_schedule_work() function. Linux kernel maintainers and users should assess exposure and prioritize verification of affected systems, especially those using the MPTCP protocol. The vulnerability can lead to system crashes or instability if exploited. Remediation requires updating to V4.0 or later version.

  • Verification of affected Linux kernel versions and MPTCP protocol usage is necessary.
  • Potential system crashes or instability if the vulnerability is exploited.
  • Remediation requires updating to V4.0 or later version of the affected product.

Technical summary

The vulnerability exists in the Linux kernel's mptcp_schedule_work() function, which schedules a work and then obtains a reference count on sk->sk_refcnt if the work was scheduled. However, if mptcp_worker() runs immediately and completes before the reference count is obtained, it can lead to a use-after-free condition. This issue arises from a race condition where a work is scheduled, and a reference count is obtained on sk->sk_refcnt if the work was scheduled. Linux kernel maintainers and users should assess exposure and prioritize verification of affected systems, especially those using the MPTCP protocol. The vulnerability can lead to system crashes or instability if exploited.

Defensive priority

Linux kernel maintainers and users should assess exposure and prioritize verification of affected systems, especially those using the MPTCP protocol.

Recommended defensive actions

  • Review and apply the vendor-provided fix by updating to V4.0 or later version.
  • Assess exposure of Linux kernel-based systems, especially those utilizing the MPTCP protocol.
  • Verify system configurations and inventory to identify potential vulnerable instances.
  • Monitor system logs for suspicious activity related to the MPTCP protocol.
  • Perform a thorough review of system configurations and network architecture to identify potential vulnerabilities.
  • Implement compensating controls, such as network segmentation or access controls, to reduce the attack surface.
  • Track and verify the remediation of vulnerable instances to ensure they are updated or mitigated.

Evidence notes

The CVE record and source item provide details about the vulnerability, including its description and potential impact. However, there is limited information about affected versions, exploitation, or remediation beyond updating to V4.0 or later.

Sources and references

Verified primary and authoritative sources

  • CVE-2025-40258 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2025-40258

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

  • CVE-2025-40258 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2025-40258

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

Supplemental references

  • CVE-2025-40258

    Unverified legacy reference

    URL: https://raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/OT/white/2026/icsa-26-188-05.json

    cisa_csaf

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/csaf/ssa-253495.json

    Supplemental source

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/html/ssa-253495.html

    Supplemental source

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/news-events/ics-advisories/icsa-26-188-05

    Supplemental source

  • Source reference

    Unverified legacy reference

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

    Supplemental source

  • Source reference

    Unverified legacy reference

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

    Supplemental source

  • Source reference

    Unverified legacy reference

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

    Supplemental source

  • Source reference

    Unverified legacy reference

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

    Supplemental source

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.