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Hitachi Energy RTU500 NULL Pointer Dereference (CVE-2026-32776)

medium Tenable OT Security Plugin ID 505380

Synopsis

The remote OT asset is affected by a vulnerability.

Description

libexpat before 2.7.5 allows a NULL pointer dereference with empty external parameter entity content, causing Denial of Service impact.

Product is only affected if IEC 61850 functionality is configured.

This plugin only works with Tenable.ot.
Please visit https://www.tenable.com/products/tenable-ot for more information.

Solution

Upgrade the RTU500 series CMU firmware to a fixed version (13.8.2, or 13.7.9 / 12.7.8 depending on the installed branch as listed in the Hitachi Energy advisory) and apply the general mitigation factors and workarounds described in the advisory.

See Also

https://www.cisa.gov/news-events/ics-advisories/icsa-26-155-04

http://www.nessus.org/u?d21730e8

Plugin Details

Severity: Medium

ID: 505380

File Name: tenable_ot_abb_CVE-2026-32776.nasl

Version: 1.2

Type: Remote

Family: Tenable.ot

Published: 6/17/2026

Updated: 6/18/2026

Supported Sensors: Tenable OT Security

Risk Information

VPR

Risk Factor: Medium

Score: 5

Percentile: 94.33

CVSS v2

Risk Factor: Medium

Base Score: 4.6

Temporal Score: 3.4

Vector: CVSS2#AV:L/AC:L/Au:S/C:N/I:N/A:C

CVSS Score Source: CVE-2026-32776

CVSS v3

Risk Factor: Medium

Base Score: 5.5

Temporal Score: 4.8

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:hitachienergy:rtu530_firmware:13.6, cpe:/o:hitachienergy:rtu530_firmware:13.8.1, cpe:/o:hitachienergy:rtu530_firmware:13.7, cpe:/o:hitachienergy:rtu530_firmware:12.7, cpe:/o:hitachienergy:rtu560_firmware:13.5, cpe:/o:hitachienergy:rtu560_firmware:13.8.1, cpe:/o:hitachienergy:rtu540_firmware:13.5, cpe:/o:hitachienergy:rtu560_firmware:13.7, cpe:/o:hitachienergy:rtu520_firmware:13.7, cpe:/o:hitachienergy:rtu540_firmware:13.8.1, cpe:/o:hitachienergy:rtu530_firmware:13.5, cpe:/o:hitachienergy:rtu540_firmware:13.6, cpe:/o:hitachienergy:rtu520_firmware:13.6, cpe:/o:hitachienergy:rtu540_firmware:12.7, cpe:/o:hitachienergy:rtu520_firmware:12.7, cpe:/o:hitachienergy:rtu520_firmware:13.8.1, cpe:/o:hitachienergy:rtu520_firmware:13.5, cpe:/o:hitachienergy:rtu560_firmware:13.6, cpe:/o:hitachienergy:rtu540_firmware:13.7, cpe:/o:hitachienergy:rtu560_firmware:12.7

Required KB Items: Tenable.ot/ABB

Exploit Ease: No known exploits are available

Patch Publication Date: 5/26/2026

Vulnerability Publication Date: 5/26/2026

Reference Information

CVE: CVE-2026-32776

CWE: 476

ICSA: 26-155-04