CVE intelligence and bounded remediation

CVE-2021-33720 — Siemens Siprotec 5 With Cpu Variant Cp050 security vulnerability

High CVSS 7.5

A vulnerability has been identified in SIPROTEC 5 relays with CPU variants CP050 (All versions < V8.80), SIPROTEC 5 relays with CPU variants CP100 (All versions < V8.80), SIPROTEC 5 relays with CPU variants CP300 (All versions < V8.80). Specially crafted packets sent to port 4443/tcp could cause a Denial-of-Service condition.

Severity
High
CVSS
7.5 (3.1)
Published
2021-09-14
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-120

Affected products

  • siemens / siprotec_5_with_cpu_variant_cp050
  • siemens / siprotec_5_with_cpu_variant_cp100
  • siemens / siprotec_5_with_cpu_variant_cp300

Matched remediation archetype

Buffer bounds, memory safety, and memory corruption

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Identify affected native-code versions, build flags, architectures, parsers, codecs, drivers, and input paths in all shipped artifacts.
  • Determine whether untrusted data reaches the affected routine and the process privilege, sandbox, and network exposure.
  • Confirm statically linked, vendored, firmware, and platform-provided copies, not only package-manager records.

Remediate safely

  • Apply the maintained upstream correction or replace the affected component, then rebuild every dependent artifact from clean inputs.
  • Adopt bounds-checked interfaces, validated sizes and integer conversions, clear ownership, and memory-safe components where practical.
  • Enable supported compiler and runtime hardening and add sanitized tests and fuzz regression seeds derived from non-weaponized fixtures.

Authoritative sources

Complete CVE record and remediation plan

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