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PatchSiren cyber security CVE debrief

CVE-2026-22795 Siemens CVE debrief

A type confusion vulnerability in PKCS#12 parsing code allows an invalid or NULL pointer dereference when processing malformed PKCS#12 files, resulting in Denial of Service. The vulnerability stems from accessing an ASN1_TYPE union member without first validating the type. The pointer manipulation is constrained to a 1-byte address space (0x00-0xFF), corresponding to the zero page which is unmapped on most modern operating systems, reliably causing crashes. Exploitation requires processing a maliciously crafted PKCS#12 file, which is uncommon in practice as PKCS#12 files typically store trusted private keys. The issue affects OpenSSL 3.6, 3.5, 3.4, 3.3, 3.0, and 1.1.1; OpenSSL 1.0.2 and FIPS modules in 3.5, 3.4, 3.3, and 3.0 are not affected. Siemens SIMATIC S7-1500 TM MFP GNU/Linux subsystem is affected. No fix is currently available.

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

Organizations operating Siemens SIMATIC S7-1500 TM MFP systems with GNU/Linux subsystems, particularly in industrial control environments where PKCS#12 files may be processed. Security teams should assess exposure to untrusted PKCS#12 file processing and implement access controls pending vendor fix availability.

Technical summary

The vulnerability exists in OpenSSL's PKCS#12 parsing implementation where ASN1_TYPE union members are accessed without type validation. This causes invalid pointer reads constrained to addresses 0x00-0xFF (the zero page), resulting in reliable crashes on modern operating systems. The attack vector requires local access with user interaction to process a malicious PKCS#12 file. CVSS 3.1: AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H (5.5 Medium).

Defensive priority

low

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 from Siemens CERT portal
  • Apply defense-in-depth strategies for industrial control systems per CISA guidance

Evidence notes

CVE published 2024-04-09; CISA CSAF advisory ICSA-24-102-01 published same date. Advisory last modified 2026-05-14 with multiple revision releases adding additional CVEs through 2025-09-09. Siemens SSA-265688 referenced as primary vendor advisory.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-22795 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-22795

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

  • CVE-2026-22795 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-22795

    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.