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 is configured. Enabling secure communication following IEC 62351-3 does not remediate the vulnerability but mitigates the risk of exploitation.

Published: 2026-02-24 Last update: 2026-05-26 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-1773 is rated Moderate Risk (46.6/100): CVSS High severity, with low exploitation likelihood (EPSS 0.41%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-1773

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.02% 0.41% +0.39%
2 2026-03-21 0.06% 0.02% -0.03%
3 2026-02-25 — 0.06% —

Full EPSS history (3 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-1773

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.7 4.0 HIGH
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network.
Attack complexity (AC:L)
Exploitation conditions are straightforward and stable.
Attack requirements (AT:N)
No additional preconditions are required beyond normal reachability.
Privileges required (PR:N)
No privileges are required.
User interaction (UI:N)
No user interaction is required.
Vulnerable system confidentiality impact (VC:N)
No confidentiality impact on the vulnerable system.
Vulnerable system integrity impact (VI:N)
No integrity impact on the vulnerable system.
Vulnerable system availability impact (VA:H)
High availability impact on the vulnerable system.
Subsequent system confidentiality impact (SC:N)
No confidentiality impact on subsequent systems.
Subsequent system integrity impact (SI:N)
No integrity impact on subsequent systems.
Subsequent system availability impact (SA:N)
No availability impact on subsequent systems.
Exploit maturity (threat) (E:X)
Not defined: no reliable threat intelligence; scoring assumes the worst case (equivalent to Attacked).
Confidentiality requirement (CR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Integrity requirement (IR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Availability requirement (AR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Modified attack vector (MAV:X)
Not defined: scoring uses the Base Attack Vector (AV).
Modified attack complexity (MAC:X)
Not defined: scoring uses the Base Attack Complexity (AC).
Modified attack requirements (MAT:X)
Not defined: scoring uses the Base Attack Requirements (AT).
Modified privileges required (MPR:X)
Not defined: scoring uses the Base Privileges Required (PR).
Modified user interaction (MUI:X)
Not defined: scoring uses the Base User Interaction (UI).
Modified vulnerable system confidentiality impact (MVC:X)
Not defined: scoring uses the Base VC metric.
Modified vulnerable system integrity impact (MVI:X)
Not defined: scoring uses the Base VI metric.
Modified vulnerable system availability impact (MVA:X)
Not defined: scoring uses the Base VA metric.
Modified subsequent system confidentiality impact (MSC:X)
Not defined: scoring uses the Base SC metric.
Modified subsequent system integrity impact (MSI:X)
Not defined: scoring uses the Base SI metric.
Modified subsequent system availability impact (MSA:X)
Not defined: scoring uses the Base SA metric.
Safety (supplemental) (S:X)
Not evaluated.
Automatable (supplemental) (AU:X)
Not evaluated.
Recovery (supplemental) (R:X)
Not evaluated.
Value density (supplemental) (V:X)
Not evaluated.
Vulnerability response effort (supplemental) (RE:X)
Not evaluated.
Provider urgency (supplemental) (U:X)
Not evaluated.
 — — [email protected]
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]

Weakness enumeration for CVE-2026-1773

Affected software / configurations for CVE-2026-1773

Vendor Product Version Raw CPE
hitachienergy rtu540_firmware >= 12.7.1, <= 12.7.7 cpe:2.3:o:hitachienergy:rtu540_firmware:*:*:*:*:*:*:*:*
hitachienergy rtu540_firmware >= 13.5.1, <= 13.5.4 cpe:2.3:o:hitachienergy:rtu540_firmware:*:*:*:*:*:*:*:*
hitachienergy rtu540_firmware >= 13.6.1, <= 13.6.2 cpe:2.3:o:hitachienergy:rtu540_firmware:*:*:*:*:*:*:*:*
hitachienergy rtu540_firmware >= 13.7.1, < 13.7.8 cpe:2.3:o:hitachienergy:rtu540_firmware:*:*:*:*:*:*:*:*
hitachienergy rtu540_firmware 13.8.1 cpe:2.3:o:hitachienergy:rtu540_firmware:13.8.1:*:*:*:*:*:*:*
hitachienergy rtu560_firmware >= 12.7.1, <= 12.7.7 cpe:2.3:o:hitachienergy:rtu560_firmware:*:*:*:*:*:*:*:*
hitachienergy rtu560_firmware >= 13.5.1, <= 13.5.4 cpe:2.3:o:hitachienergy:rtu560_firmware:*:*:*:*:*:*:*:*
hitachienergy rtu560_firmware >= 13.6.1, <= 13.6.2 cpe:2.3:o:hitachienergy:rtu560_firmware:*:*:*:*:*:*:*:*
hitachienergy rtu560_firmware >= 13.7.1, < 13.7.8 cpe:2.3:o:hitachienergy:rtu560_firmware:*:*:*:*:*:*:*:*
hitachienergy rtu560_firmware 13.8.1 cpe:2.3:o:hitachienergy:rtu560_firmware:13.8.1:*:*:*:*:*:*:*
hitachienergy rtu520_firmware >= 12.7.1, <= 12.7.7 cpe:2.3:o:hitachienergy:rtu520_firmware:*:*:*:*:*:*:*:*
hitachienergy rtu520_firmware >= 13.5.1, <= 13.5.4 cpe:2.3:o:hitachienergy:rtu520_firmware:*:*:*:*:*:*:*:*
hitachienergy rtu520_firmware >= 13.6.1, <= 13.6.2 cpe:2.3:o:hitachienergy:rtu520_firmware:*:*:*:*:*:*:*:*
hitachienergy rtu520_firmware >= 13.7.1, < 13.7.8 cpe:2.3:o:hitachienergy:rtu520_firmware:*:*:*:*:*:*:*:*
hitachienergy rtu520_firmware 13.8.1 cpe:2.3:o:hitachienergy:rtu520_firmware:13.8.1:*:*:*:*:*:*:*
hitachienergy rtu530_firmware >= 12.7.1, <= 12.7.7 cpe:2.3:o:hitachienergy:rtu530_firmware:*:*:*:*:*:*:*:*
hitachienergy rtu530_firmware >= 13.5.1, <= 13.5.4 cpe:2.3:o:hitachienergy:rtu530_firmware:*:*:*:*:*:*:*:*
hitachienergy rtu530_firmware >= 13.6.1, <= 13.6.2 cpe:2.3:o:hitachienergy:rtu530_firmware:*:*:*:*:*:*:*:*
hitachienergy rtu530_firmware >= 13.7.1, < 13.7.8 cpe:2.3:o:hitachienergy:rtu530_firmware:*:*:*:*:*:*:*:*
hitachienergy rtu530_firmware 13.8.1 cpe:2.3:o:hitachienergy:rtu530_firmware:13.8.1:*:*:*:*:*:*:*

References for CVE-2026-1773

cvelogic Threat Intelligence