# CVE-2026-17539

## Summary

- **CVE ID:** CVE-2026-17539
- **Severity:** MEDIUM
- **CVSS Score:** 5.9 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H)
- **CWE:** CWE-476
- **Published:** Sep 3, 2026
- **Last Modified:** Sep 3, 2026

## Description

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.

## Affected Products

- Hitachi Energy — RTU500 series CMU firmware (12.7.1)
- Hitachi Energy — RTU500 series CMU firmware (13.5.1)
- Hitachi Energy — RTU500 series CMU firmware (13.6.1)
- Hitachi Energy — RTU500 series CMU firmware (13.7.1)
- Hitachi Energy — RTU500 series CMU firmware (13.8.1)

## References

- [CNA](https://publisher.hitachienergy.com/preview?DocumentID=8DBD000259&LanguageCode=en&DocumentPartId=&Action=Launch)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.35%
- **EPSS Percentile:** 28.1

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._