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PatchSiren cyber security CVE debrief

CVE-2024-50127 Siemens CVE debrief

A use-after-free vulnerability in the Linux kernel's taprio traffic scheduler (net/sched) allows local attackers to corrupt memory and potentially escalate privileges. The flaw occurs in taprio_change() where the 'admin' pointer can become dangling due to race conditions between schedule switching/removal and pointer updates. The critical section protected by q->current_entry_lock is insufficient to prevent this scenario, which was detected by KASAN. The vulnerability affects Siemens SIMATIC S7-1500 TM MFP industrial control systems running the GNU/Linux subsystem.

Vendor
Siemens
Product
SIMATIC S7-1500 TM MFP - GNU/Linux subsystem
CVSS
HIGH 7.8
CISA KEV
Not listed in stored evidence
Original CVE published
2024-04-09
Original CVE updated
2026-05-14
Advisory published
2024-04-09
Advisory updated
2026-05-14

Who should care

Industrial control system operators using Siemens SIMATIC S7-1500 TM MFP with GNU/Linux subsystem; Linux kernel maintainers for networking subsystem; OT security teams managing time-sensitive networking (TSN) implementations; organizations using taprio for deterministic Ethernet scheduling in critical infrastructure.

Technical summary

The vulnerability exists in the taprio (Time-Aware Priority Shaper) network scheduler in the Linux kernel. The taprio_change() function manages administrative schedule configurations through an 'admin' pointer. During schedule advancement via advance_sched(), concurrent operations can cause the 'admin' pointer to reference freed memory. The existing locking mechanism (q->current_entry_lock) does not adequately protect against this race condition. The fix replaces rcu_assign_pointer() with rcu_replace_pointer() to ensure immediate pointer update before scheduling memory freeing, preventing the dangling pointer scenario. This is a classic RCU (Read-Copy-Update) synchronization issue where the grace period and pointer update ordering creates a window for use-after-free access.

Defensive priority

HIGH

Recommended defensive actions

  • Limit access to the interactive shell of the additional GNU/Linux subsystem to trusted personnel only
  • Only build and run applications from trusted sources
  • Monitor for vendor security updates as no patch is currently available
  • Apply defense-in-depth strategies for industrial control systems per CISA guidance
  • Review network segmentation to limit exposure of affected systems

Evidence notes

CVE published 2024-04-09. CISA ICS advisory ICSA-24-102-01 published same date. Advisory last modified 2026-05-14 with multiple additional releases through September 2025 adding related CVEs. Siemens SSA-265688 provides vendor-specific guidance. CVSS 3.1 vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

Sources and references

Verified primary and authoritative sources

  • CVE-2024-50127 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2024-50127

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

  • CVE-2024-50127 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2024-50127

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

Supplemental references

  • Source item URL

    Unverified legacy reference

    URL: https://raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/OT/white/2024/icsa-24-102-01.json

    cisa_csaf

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/csaf/ssa-265688.json

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/html/ssa-265688.html

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/news-events/ics-advisories/icsa-24-102-01

    Reference

  • Source reference

    Unverified legacy reference

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

    Reference

  • Source reference

    Unverified legacy reference

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

    Reference

  • Source reference

    Unverified legacy reference

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

    Reference

  • Source reference

    Unverified legacy reference

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

    Reference

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.