Hitachi Energy REB500 Vulnerabilities: Two libexpat Flaws Patched in Version 8.3.4.0

Hitachi Energy is aware of open-source software vulnerabilities that affect REB500 product versions listed in this document. These vulnerabilities can be exploited to carry out Denial of Service (DoS) attack on the product. The following versions of Hitachi Energy REB500 are affected: REB500/<=8.3.3.1 (CVE-2024-8176, CVE-2025-59375).

CVE-2024-8176: A stack overflow vulnerability exists in the libexpat library used by the IEC61850 functionality supported by REB500 product. An authenticated malicious user with local access could use a crafted IEC 61850 message to exploit the vulnerability in the libexpat library. This issue could lead to denial of service (DoS) or, in some cases, exploitable memory corruption, depending on the environment and library usage. The relevant CWE is CWE-674 (Uncontrolled Recursion). CVSS v3.1 Base Score: 6.5 (MEDIUM), Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

CVE-2025-59375: libexpat in Expat before 2.7.2 used by the IEC 61850 functionality supported by the REB500 product allows authenticated users to trigger large dynamic memory allocations via a small document that is submitted for parsing. The relevant CWE is CWE-770 (Allocation of Resources Without Limits or Throttling). CVSS v3.1 Base Score: 6.5 (MEDIUM), Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

Both vulnerabilities affect REB500 versions 8.3.3.1 and prior. Hitachi Energy has remediated the issues in version 8.3.4.0. The vendor reported the vulnerabilities to CISA.

Critical Infrastructure Sectors: Energy. Countries/Areas Deployed: Worldwide. Company Headquarters Location: Switzerland.