CVE-2026-17539Network attack vector

Communication denial via message queue NULL dereference

Published Sep 3, 2026 · Updated Sep 3, 2026

NULL pointer dereference in Hitachi Energy RTU500 Series CMU Firmware allows remote attackers to interrupt IEC 60870-5-104 communication. Under high load, closely spaced GI requests cause the last entry in the enhanced message queue to dereference NULL, producing a BCI_IEC104 fatal write error. Network access and sustained request timing are required; successful triggering interrupts and restarts the connection, denying bidirectional communication.

CVSS severity5.9
Medium
EPSS probability0.35%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in Hitachi Energy RTU500 Series CMU Firmware allows remote attackers to interrupt IEC 60870-5-104 communication. Under high load, closely spaced GI requests cause the last entry in the enhanced message queue to dereference NULL, producing a BCI_IEC104 fatal write error. Network access and sustained request timing are required; successful triggering interrupts and restarts the connection, denying bidirectional communication.

The record

CVE
CVE-2026-17539
Published
Sep 3, 2026
Updated
Sep 3, 2026
Vendor
Hitachi Energy
Product
RTU500 Series CMU Firmware
Classifications
CWE-476, CAPEC-679, T0814
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 3, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 3, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=12.7.1 <=12.7.7
  2. Affected versionversion=13.5.1 <=13.5.4
  3. Affected versionversion=13.6.1 <=13.6.3
  4. Affected versionversion=13.7.1 <=13.7.8
  5. Affected versionversion=13.8.1 <=13.8.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Hitachi Energy · RTU500 Series CMU Firmwareversion=12.7.1 <=12.7.7; version=13.5.1 <=13.5.4; version=13.6.1 <=13.6.3; version=13.7.1 <=13.7.8; version=13.8.1 <=13.8.2

Published CVSS scores

5.9Hitachi EnergyCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
CAPEC-679Exploitation of Improperly Configured or Implemented Memory Protections
T0814Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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