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CVE-2024-35886 Siemens CVE debrief

CVE-2024-35886 is a vulnerability in the Linux kernel's IPv6 networking subsystem that could cause a denial of service through infinite recursion. The flaw exists in fib6_dump_done(), which could recursively call itself during netlink socket destruction under specific fault conditions, eventually exhausting the kernel stack and causing a crash. The vulnerability was triggered when a netlink dump operation for IPv6 routing information failed at memory allocation (kzalloc()), leaving a callback function pointer in an inconsistent state. When the socket was later destroyed, the callback mechanism would recursively invoke fib6_dump_done(), which would restore the same callback pointer from saved arguments, creating an infinite loop until the stack guard page was hit. The fix involves setting the destructor callback only after successful memory allocation to prevent this state inconsistency. Siemens has identified this vulnerability as affecting the GNU/Linux subsystem in SIMATIC S7-1500 TM MFP industrial control devices. The vulnerability has a CVSS 3.1 score of 5.5 (MEDIUM severity) with a local attack vector, low attack complexity, and low privileges required, with high impact on availability. No patch is currently available from Siemens; mitigations focus on restricting access to the interactive shell and ensuring only trusted applications are executed.

Vendor
Siemens
Product
SIMATIC S7-1500 TM MFP - GNU/Linux subsystem
CVSS
MEDIUM 5.5
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

System administrators managing Siemens SIMATIC S7-1500 TM MFP industrial control systems with the GNU/Linux subsystem enabled; security teams responsible for OT/ICS infrastructure; Linux kernel maintainers and distributors packaging kernel versions prior to the fix

Technical summary

The vulnerability stems from improper callback state management in the Linux kernel's IPv6 forwarding information base (FIB) dump mechanism. When inet6_dump_fib() fails during kzalloc() due to memory pressure or fault injection, the fib6_dump_done() callback is already registered in nlk_sk(sk)->cb.done but the cleanup state in cb.args[3] points to the same function. During netlink socket destruction, fib6_dump_done() calls fib6_dump_end(), which restores cb.done from cb.args[3], creating a self-referential loop. Each recursive call consumes stack space until the guard page is reached, triggering a kernel oops or panic. The fix relocates the destructor assignment to occur only after successful memory allocation, ensuring state consistency.

Defensive priority

medium

Recommended defensive actions

  • Restrict interactive shell access to the GNU/Linux subsystem on affected Siemens SIMATIC S7-1500 TM MFP devices to trusted personnel only
  • Ensure only applications from trusted sources are built and executed on the GNU/Linux subsystem
  • Monitor for kernel crashes or stack overflow indicators in system logs that may indicate exploitation attempts
  • Apply vendor patches when released by Siemens
  • Review and implement CISA ICS recommended practices for defense-in-depth strategies

Evidence notes

Vulnerability description and technical details sourced from CISA CSAF advisory ICSA-24-102-01 and Siemens security advisory SSA-265688. The vulnerability was originally discovered by syzkaller and fixed in the upstream Linux kernel. Siemens product impact confirmed through CSAF product tree with high confidence.

Sources and references

Verified primary and authoritative sources

  • CVE-2024-35886 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2024-35886

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

  • CVE-2024-35886 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2024-35886

    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.