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CVE-2022-36324 Siemens CVE debrief

CVE-2022-36324 affects multiple Siemens SCALANCE wireless devices and is rated HIGH (CVSS 7.5). According to the advisory, affected devices do not properly handle SSL/TLS parameter renegotiation, which can let an unauthenticated remote attacker bypass TCP brute-force prevention and sustain a denial-of-service condition for as long as the attack continues. Siemens lists firmware V6.6.0 or later as the fix for the affected product set.

Vendor
Siemens
Product
SCALANCE W721-1 RJ45 (6GK5721-1FC00-0AA0)
CVSS
HIGH 7.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-04-14
Original CVE updated
2026-04-21
Advisory published
2026-04-14
Advisory updated
2026-04-21

Who should care

OT/ICS defenders, Siemens SCALANCE administrators, network security teams, and incident responders responsible for industrial wireless infrastructure should prioritize this issue, especially where the listed W721/W722/W734/W738/W748/W761/W774/W778/W786/W788 models are deployed.

Technical summary

The issue is a network-exploitable availability weakness: CVSS v3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. The advisory states that SSL/TLS renegotiation is not handled properly, allowing an unauthenticated remote attacker to bypass TCP brute-force prevention. The practical outcome described by the source is a denial-of-service condition during the attack window, with no confidentiality or integrity impact indicated in the vector.

Defensive priority

High for exposed OT networks and any environment where the affected SCALANCE devices are reachable from untrusted networks. Remediation is straightforward if firmware updates are operationally feasible, but change-control and downtime constraints in OT may delay replacement of vulnerable firmware.

Recommended defensive actions

  • Upgrade affected devices to Siemens firmware V6.6.0 or later, as directed in the advisory.
  • Identify all deployed SCALANCE models listed in the advisory and confirm current firmware versions before scheduling maintenance.
  • Restrict network exposure to management and TLS-enabled services; do not leave device interfaces unnecessarily reachable from untrusted networks.
  • Monitor for repeated connection attempts, authentication brute-force patterns, or service instability affecting the impacted devices.
  • Use OT segmentation and defense-in-depth controls to reduce attacker reach if immediate patching is not possible.

Evidence notes

All substantive claims are taken from the supplied CISA CSAF advisory and the referenced Siemens ProductCERT materials. The source explicitly states the TLS renegotiation handling issue, unauthenticated remote bypass of TCP brute-force prevention, resulting denial of service, affected SCALANCE models, and the vendor remediation to update to V6.6.0 or later. The CVSS vector is also provided in the source as CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:P/RL:O/RC:C.

Sources and references

Verified primary and authoritative sources

  • CVE-2022-36324 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2022-36324

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

  • CVE-2022-36324 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2022-36324

    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/2026/icsa-26-111-07.json

    cisa_csaf

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/csaf/ssa-019200.json

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/html/ssa-019200.html

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/news-events/ics-advisories/icsa-26-111-07

    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.