High severity · published Feb 24, 2026
CVE-2026-1773
IEC 60870-5-104 used in RTU500: Potential Denial of Service impact on reception of invalid U-format frame. Product is only affected if IEC 60870-5-104 bi-directional functionality…
7.5
CVSS
0.5%
EPSS
No
On KEV
Description
IEC 60870-5-104 used in RTU500: Potential Denial of Service impact on reception of invalid U-format frame. Product is only affected if IEC 60870-5-104 bi-directional functionality is configured. Enabling secure communication following IEC 62351-3 does not remediate the vulnerability but mitigates the risk of exploitation.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 39% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
RS
RTU500 series CMU firmware · Hitachi Energy
12.7.1 through 12.7.7; 13.5.1 through 13.5.4; 13.6.1 through 13.6.2; 13.7.1 through 13.7.7; 13.8.1 · source: vendor
RF
Rtu520 Firmware · Hitachienergy
12.7.1 through 12.7.7; 13.5.1 through 13.5.4; 13.6.1 through 13.6.2; 13.7.1 before 13.7.8; 13.8.1 · source: NVD
RF
Rtu530 Firmware · Hitachienergy
12.7.1 through 12.7.7; 13.5.1 through 13.5.4; 13.6.1 through 13.6.2; 13.7.1 before 13.7.8; 13.8.1 · source: NVD
RF
Rtu540 Firmware · Hitachienergy
12.7.1 through 12.7.7; 13.5.1 through 13.5.4; 13.6.1 through 13.6.2; 13.7.1 before 13.7.8; 13.8.1 · source: NVD
RF
Rtu560 Firmware · Hitachienergy
12.7.1 through 12.7.7; 13.5.1 through 13.5.4; 13.6.1 through 13.6.2; 13.7.1 before 13.7.8; 13.8.1 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-1773
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-1773
Vendor Advisory
https://publisher.hitachienergy.com/preview?DocumentID=8DBD000237&LanguageCode=en&DocumentPartId=&Action=Launch
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