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Fencer Vulns
high 7.5

CVE-2021-37206 json

A vulnerability has been identified in SIPROTEC 5 relays with CPU variants CP050 (All versions < V8.80), SIPROTEC 5 relays with CPU variant…

published 2021-09-14 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-23780

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.4%
EPSS 1.4% chance of exploitation in 30 days, percentile 73%
public exploits
0
none known

Summary

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). Received webpackets are not properly processed. An unauthenticated remote attacker with access to any of the Ethernet interfaces could send specially crafted packets to force a restart of the target device.

Patch / fix

  • siemens siprotec_5_with_cpu_variant_cp050 8.80
  • siemens siprotec_5_with_cpu_variant_cp100 8.80
  • siemens siprotec_5_with_cpu_variant_cp300 8.80

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

cisa ICSA-21-257-16 updated cvss 7.5

Siemens SIPROTEC 5 (Update A)

  • Siemens SIPROTEC 5 relays with CPU variants CP050 <V8.80 Siemens SIPROTEC 5 relays with CPU variants CP100 <V8.80 Siemens SIPROTEC 5 relays with CPU variants CP300 <V8.80
    affected: fixed in V8.80, mitigation support.industry.siemens.com

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

Exploit prediction

1.43% chance of exploitation in the next 30 days, higher than 73% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P

Affected products

  • Siemens SIPROTEC 5 relays with CPU variants CP050
  • Siemens SIPROTEC 5 relays with CPU variants CP100
  • Siemens SIPROTEC 5 relays with CPU variants CP300

Classification

Weakness
  • CWE-20 Improper Input Validation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.