8.7

CVE-2026-1773: hitachi energy rtu500 series cmu firmware Incomplete List of Disallowed Inputs

CVSS: 8.7v4.0HighModified
Published 24-02-2026Last modified 27-05-2026
Open JSON

Vulnerability summary

CVE-2026-1773 is a high (CVSS 8.7) Incomplete List of Disallowed Inputs vulnerability in hitachi energy rtu500 series cmu firmware. EPSS estimates a 0.43% chance of exploitation in the next 30 days, higher than 35.6% of scored vulnerabilities.

Overall risk
35/100
0100
Medium · default modelHow is this calculated?
CVSS score
8.7/10
010
High · v4.0 (CVE.org)
EPSS score
0.43%
0%100%
Low · +0.02 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 24-02-2026
    PublishedVulnerability first disclosed.
  2. 27-05-2026
    Last modifiedVulnerability information updated.

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 metrics

3 scores · 2 sources · 2 versions

EPSS trend

Probability

0.43%

Chance of exploitation in the next 30 days

Percentile

36%

Versus all other CVEs

30-day change

+0.02 pp

From 0.41% on 20-09-2026

20-09-202620-10-2026
EPSS score
0.43%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Hitachienergy4 products
  • rtu520_firmware≥ 12.7.1, ≤ 12.7.7 | ≥ 13.5.1, ≤ 13.5.4 | ≥ 13.6.1, ≤ 13.6.2 | ≥ 13.7.1, < 13.7.8 | 13.8.1
  • rtu530_firmware≥ 12.7.1, ≤ 12.7.7 | ≥ 13.5.1, ≤ 13.5.4 | ≥ 13.6.1, ≤ 13.6.2 | ≥ 13.7.1, < 13.7.8 | 13.8.1
  • rtu540_firmware≥ 12.7.1, ≤ 12.7.7 | ≥ 13.5.1, ≤ 13.5.4 | ≥ 13.6.1, ≤ 13.6.2 | ≥ 13.7.1, < 13.7.8 | 13.8.1
  • rtu560_firmware≥ 12.7.1, ≤ 12.7.7 | ≥ 13.5.1, ≤ 13.5.4 | ≥ 13.6.1, ≤ 13.6.2 | ≥ 13.7.1, < 13.7.8 | 13.8.1
Hitachi energy1 product
  • rtu500 series cmu firmware≥ 12.7.1, ≤ 12.7.7 | ≥ 13.5.1, ≤ 13.5.4 | ≥ 13.6.1, ≤ 13.6.2 | ≥ 13.7.1, ≤ 13.7.7 | 13.8.1

2 vendors · 5 products

References

1 links