Hitachi Energy RTU500 CMU firmware contains multiple denial-of-service vulnerabilities in…

Hitachi Energy RTU500 CMU firmware contains multiple denial-of-service vulnerabilities in certificate parsing and IEC protocol handlers affecting critical infrastructure worldwide.

CISA published an advisory detailing seven vulnerabilities in Hitachi Energy RTU500 series Communication Management Unit (CMU) firmware used in critical infrastructure across dams, energy, and water sectors globally. The vulnerabilities primarily enable denial-of-service attacks through NULL pointer dereferences in OpenSSL's PKCS#12 certificate processing (CVE-2025-69421), multiple flaws in libexpat XML parsing affecting IEC 61850 functionality (CVE-2026-24515, CVE-2026-25210, CVE-2026-32776, CVE-2026-32777, CVE-2026-32778), and a protocol-specific vulnerability in IEC 60870-5-104 bidirectional communication (CVE-2026-8479). Affected firmware versions span 12.7.1 through 13.8.1 across multiple release branches.

Exploitation requires specific configuration conditions: the PKCS#12 flaw requires privileged user access to upload malformed certificates or configured PKI client functionality, while the libexpat vulnerabilities only affect systems with IEC 61850 enabled, and the IEC 60870-5-104 flaw requires bidirectional mode configuration. Primary impact is availability loss through crashes and infinite loops, with CVE-2026-25210 potentially affecting confidentiality and integrity through integer overflow. Hitachi Energy recommends immediate upgrade to CMU firmware version 13.8.2, or version 13.7.9 when available, alongside standard ICS defense-in-depth practices including network isolation and restricted remote access.

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