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Fencer Intel
high 7.5

CVE-2021-35533 json

Specially Crafted IEC 60870-5-104 Packet Vulnerability in RTU500 series

published 4y ago modified 4mo ago also EUVD-2021-22169

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.0%
EPSS 1.0% chance of exploitation in 30 days, percentile 61%
public exploits
0
none known

Summary

Improper Input Validation vulnerability in the APDU parser in the Bidirectional Communication Interface (BCI) IEC 60870-5-104 function of Hitachi Energy RTU500 series allows an attacker to cause the receiving RTU500 CMU of which the BCI is enabled to reboot when receiving a specially crafted message. By default, BCI IEC 60870-5-104 function is disabled (not configured). This issue affects: Hitachi Energy RTU500 series CMU Firmware version 12.0.* (all versions); CMU Firmware version 12.2.* (all versions); CMU Firmware version 12.4.* (all versions).

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Vendor advisories

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

cisa ICSA-21-336-04 updated cvss 7.5

Hitachi Energy RTU500 series BCI

  • Hitachi Energy RTU500 series CMU Firmware Version 12.0 Hitachi Energy RTU500 series CMU Firmware Version 12.2 Hitachi Energy RTU500 series CMU Firmware Version 12.4
    affected: mitigation “Disable BCI IEC 60870-5-104 function by configuration if it is not used. Note: By default, the BCI IEC 60870-5-104 is disabled.” search.abb.com

From CISA ICS and IT advisories (CSAF, https://github.com/cisagov/CSAF), a U.S. Government work; changed: reduced to products, statuses and remediations. CISA notification · csaf

Exploit prediction

0.95% chance of exploitation in the next 30 days, higher than 61% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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 7.1 AV:N/AC:M/Au:N/C:N/I:N/A:C

Affected products

  • Hitachi Energy RTU500 series

Classification

Weakness
  • CWE-20 Improper Input Validation

References

Sources

Fencer Intel 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.