PatchSiren

PatchSiren cyber security CVE debrief

CVE-2024-33601 Siemens CVE debrief

CVE-2024-33601 is a denial-of-service vulnerability in the GNU C Library nscd netgroup cache. According to the supplied advisory material, memory allocation failures in xmalloc or xrealloc can terminate the nscd process, disrupting clients that depend on it. Siemens’ advisory context ties the issue to specific SIMATIC S7-1500 CPU variants that include an additional GNU/Linux subsystem. The flaw was introduced in glibc 2.15 when the cache was added to nscd, and the supplied source states that no fix was available at the time of publication.

Vendor
Siemens
Product
SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)
CVSS
MEDIUM 4
CISA KEV
Not listed in stored evidence
Original CVE published
2025-06-10
Original CVE updated
2026-05-14
Advisory published
2025-06-10
Advisory updated
2026-05-14

Who should care

Operators and maintainers of the listed Siemens SIMATIC S7-1500 CPU 1518-4/1518F-4 PN/DP MFP variants and SIPLUS variant, especially teams that enable or manage the additional GNU/Linux subsystem, should review exposure. Security and operations teams that rely on nscd for name service caching should also care because the impact is service disruption rather than data compromise.

Technical summary

The issue is in nscd’s netgroup cache handling: xmalloc or xrealloc may terminate the daemon on memory allocation failure. The supplied CVE description states this can deny service to clients and that the problem is only present in the nscd binary. The CVSS vector provided is CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L, which aligns with a local availability-only impact.

Defensive priority

Medium priority. The vulnerability is availability-only and local, but the affected Siemens products have no fix available in the supplied source and the advisory recommends compensating controls.

Recommended defensive actions

  • Confirm whether the listed Siemens SIMATIC S7-1500 CPU variants are present in your environment and whether the additional GNU/Linux subsystem is enabled.
  • Limit access to the interactive shell of the additional GNU/Linux subsystem to trusted personnel only, as recommended in the advisory.
  • Only build and run applications from trusted sources on the affected system, per the advisory guidance.
  • Monitor Siemens ProductCERT and CISA advisory updates for any future remediation or revised guidance.
  • Treat nscd-dependent services as availability-sensitive and plan compensating controls or operational fallback if the daemon terminates.

Evidence notes

This debrief is based on the supplied CISA CSAF advisory ICSA-25-162-05 and Siemens ProductCERT advisory SSA-082556 references. The supplied source lists affected Siemens products as SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0, 6ES7518-4AX00-1AC0), SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0, 6ES7518-4FX00-1AC0), and SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0). The advisory states there is currently no fix available. Timing context used here follows the supplied CVE publication date of 2025-06-10 and modified date of 2026-05-14.

Sources and references

Verified primary and authoritative sources

  • CVE-2024-33601 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2024-33601

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

  • CVE-2024-33601 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2024-33601

    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/2025/icsa-25-162-05.json

    cisa_csaf

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/csaf/ssa-082556.json

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/html/ssa-082556.html

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/news-events/ics-advisories/icsa-25-162-05

    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.