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Rtu540 FirmwareOperating system · Hitachienergy

CVE-2026-1773

HIGH · 7.5 CVSS v3.1 Published 2026-02-24
Fix available
A fix is available. Upgrade to 13.7.8 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The IEC 60870-5-104 protocol implementation in RTU500 products contains a vulnerability where reception of an invalid U-format frame can cause a Denial of Service condition. The U-format frames in IEC 60870-5-104 are used for activation/deactivation commands (STARTDT, STOPDT, TESTFR). The issue only manifests when bi-directional functionality is configured. Notably, IEC 62351-3 secure communication does not remediate the flaw, indicating the vulnerability is in the protocol parsing logic itself rather than in authentication.

MitigationApply vendor-supplied firmware/software patch for RTU500; until patch available, consider disabling bi-directional IEC 60870-5-104 functionality if operationally feasible, though this may limit functionality. IEC 62351-3 provides only risk mitigation, not remediation.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Rtu540 FirmwareOperating system
Affected:>= 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 FirmwareOperating system
Affected:>= 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
Rtu520 FirmwareOperating system
Affected:>= 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 FirmwareOperating system
Affected:>= 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

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the RTU500 product model
    Locate the device model identifier in the system information, administrative interface, or device labeling
    Affected if Device is not one of: RTU540, RTU560, RTU520, or RTU530
  2. Determine the installed firmware version
    Access the firmware version through the device management interface or system status menu
    Affected if Version falls within any of these ranges: 12.7.1 to 12.7.7, 13.5.1 to 13.5.4, 13.6.1 to 13.6.2, 13.7.1 to 13.7.7, or equals 13.8.1
  3. Check bi-directional IEC 60870-5-104 configuration
    Review the IEC 60870-5-104 protocol settings to determine whether bi-directional communication mode is enabled
    Affected if Bi-directional functionality is configured and active for the IEC 60870-5-104 protocol

Device is affected only if it is an RTU540/560/520/530 with an affected firmware version AND bi-directional IEC 60870-5-104 is enabled.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 13.7.8 or later
Fixed in 13.7.8
Interim mitigation

Apply vendor-supplied firmware/software patch for RTU500; until patch available, consider disabling bi-directional IEC 60870-5-104 functionality if operationally feasible, though this may limit functionality. IEC 62351-3 provides only risk mitigation, not remediation.

Recommended fix High confidence

Firmware version 13.7.8 or later for Rtu540/Rtu560/Rtu520/Rtu530

  1. 1. Log into the RTU device web interface or management console
  2. 2. Navigate to the firmware management or system update section
  3. 3. Download the firmware update from Hitachi Energy's official support portal (publisher.hitachienergy.com) for your specific RTU model (Rtu540, Rtu560, Rtu520, or Rtu530)
  4. 4. Upload the firmware version 13.7.8 or later to the device
  5. 5. Initiate the firmware update process and wait for completion
  6. 6. Verify the firmware version has been updated successfully
  7. 7. Restart the device if required
  8. 8. Confirm IEC 60870-5-104 functionality is operating normally after the update
Caveat Review Hitachi Energy release notes for any changes to IEC 60870-5-104 functionality or configuration requirements in the new firmware version

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Rtu540 Firmware Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing12.0 h
  • Review / QA4.0 h
28.0 hours of engineering $4,760
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-1773 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data