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Vulnerabilities

Vulnerability · CVE-2026-17539

RTU500 has a vulnerability, where high-load scenarios, such as sending GI requests at short intervals, may cause a NULL pointer dereference in the last entry of the en…

Published Sep 3, 2026 · catalog updated Sep 3, 2026 · Hitachi Energy RTU500 series CMU firmware

Last checked Oct 25, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-17539. EPSS is 0.37%. Act only if a listed version of Hitachi Energy RTU500 series CMU firmware is installed.

Gaps on this record

  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium5.9
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.37%
Remediation
Not established
Affected products
vendor Hitachi Energy RTU500 series CMU firmware

RTU500 has a vulnerability, where high-load scenarios, such as sending GI requests at short intervals, may cause a NULL pointer dereference in the last entry of the enhanced message queue. This can cause a BCI_IEC104 fatal write error, resulting in connection interruption and restart, and ultimately a denial of service for bidirectional IEC 60870-5-104 communication.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • vendor Hitachi Energy RTU500 series CMU firmwareversion unspecified

How to fix CVE-2026-17539

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-17539. EPSS is 0.37%. Act only if a listed version of Hitachi Energy RTU500 series CMU firmware is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-476: NULL Pointer Dereference. EPSS 0.37%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Sep 3, 2026 · CVE.org

    Updated

    RTU500 has a vulnerability, where high-load scenarios, such as sending GI requests at short intervals, may cause a NULL pointer dereference in the last entry of the enhanced message queue. This can cause a BCI_IEC104 fatal write error, resulting in connection interruption and restart, and ultimately a denial of service for bidirectional IEC 60870-5-104 communication.

  2. Oct 20, 2026 · CISA ICS Advisories

    Detected

    CVE-2026-17539 is listed by Hitachi Energy RTU500 Product.

Sources

  • CISA Cybersecurity AdvisoriesGovernment advisoryCVE-2026-17539

    View CSAF Summary Hitachi Energy is aware of vulnerabilities that affect RTU500 product versions listed in this document. These vulnerabilities if exploited can have impact on confidentiality, integrity and availability of the product. Please refer to the Recommended Immediate Ac

    cisa.gov
  • CISA ICS AdvisoriesGovernment advisoryCVE-2026-17539

    View CSAF Summary Hitachi Energy is aware of vulnerabilities that affect RTU500 product versions listed in this document. These vulnerabilities if exploited can have impact on confidentiality, integrity and availability of the product. Please refer to the Recommended Immediate Ac

    cisa.gov
  • CVE.orgVulnerability recordCVE-2026-17539

    RTU500 has a vulnerability, where high-load scenarios, such as sending GI requests at short intervals, may cause a NULL pointer dereference in the last entry of the enhanced message queue. This can cause a BCI_IEC104 fatal write error, resulting in connection interruption and res

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-17539

    30-day exploitation probability 0.37%

    first.org

References

Freshness

Last verified in this catalog Oct 25, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • FIRST EPSSOct 25, 2026
  • CISA Cybersecurity AdvisoriesOct 23, 2026
  • CVE.orgOct 23, 2026
  • CISA ICS AdvisoriesOct 23, 2026