Is CVE-2026-1773 in the CISA KEV catalog?

No. CVE-2026-1773 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-1773?

CVE-2026-1773 has a CVSS v3 base score of 7.5 (HIGH).

What is the EPSS score for CVE-2026-1773?

CVE-2026-1773 has an EPSS score of 0.41% (33th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-1773?

Upgrade rtu520 firmware to 13.7.8 or later. Fixes are available for 4 affected products.

CVE & CISA-KEV Catalog

CVE-2026-1773

HIGH

7.5

CVSS v3

NVD

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.

CWE-184

How to fix

Remediation Available

rtu520 firmwareNVD

Affected:>= 13.7.1, < 13.7.8Fixed in:13.7.8CVE-2026-1773derived from NVD

rtu530 firmwareNVD

Affected:>= 13.7.1, < 13.7.8Fixed in:13.7.8CVE-2026-1773derived from NVD

rtu540 firmwareNVD

Affected:>= 13.7.1, < 13.7.8Fixed in:13.7.8CVE-2026-1773derived from NVD

rtu560 firmwareNVD

Affected:>= 13.7.1, < 13.7.8Fixed in:13.7.8CVE-2026-1773derived from NVD

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityHigh

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploit Intelligence

0.41%probability of exploitation in 30 days

33rdpercentile

Low risk: more likely to be exploited than 33% of all known CVEs.

References

Vendor Advisory1

publisher.hitachienergy.com

Related Vulnerabilities

Other CWE-184 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2024-5217	Critical	9.8	100%	KEV	-
CVE-2022-43396	High	8.8	57%	-	Fix
CVE-2017-7525	Critical	9.8	38%	-	Fix
CVE-2024-5178	Medium	4.9	34%	-	-
CVE-2018-7489	Critical	9.8	20%	-	Fix
CVE-2018-6383	High	8.8	13%	-	-

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-05-26.