Security readout for executives and security teams
Plain-English summary
This issue can let a remote unauthenticated actor cause denial of service in affected Hitachi Energy RTU500 CMU firmware when IEC 60870-5-104 bidirectional functionality is configured. The business concern is loss of availability in industrial control environments, not data theft.
Executive priority
Treat as high priority for utilities or industrial sites using affected RTU500 firmware with bidirectional IEC 60870-5-104 enabled. Focus on operational availability, asset inventory, and vendor-approved remediation planning.
Technical view
CVE-2026-1773 is a CWE-184 incomplete list of disallowed inputs issue affecting IEC 60870-5-104 handling in RTU500 CMU firmware. An invalid U-format frame may cause denial of service. CVSS 4.0 is 8.7 with network attack vector, low complexity, no privileges, and high availability impact.
Likely exposure
Exposure appears limited to listed RTU500 CMU firmware versions 12.7.1, 13.5.1, 13.6.1, 13.7.1, and 13.8.1, only when IEC 60870-5-104 bidirectional functionality is configured.
Exploitation context
The source bundle does not report active exploitation, and CISA KEV status is false. The vulnerability is remotely reachable over the network under the affected configuration, with no privileges or user interaction required.
Researcher notes
Evidence is concise but clear on affected versions, prerequisite configuration, and availability impact. No public exploit status, patch version, or detailed root-cause analysis is provided in the source bundle.
Mitigation direction
- Check Hitachi Energy guidance for fixed firmware or official remediation.
- Inventory RTU500 CMU firmware versions against the affected version list.
- Remove IEC 60870-5-104 bidirectional functionality where not operationally required.
- Use IEC 62351-3 secure communication as risk reduction, not remediation.
- Prioritize compensating controls for exposed operational networks.
Validation and detection
- Confirm whether RTU500 CMU firmware matches an affected listed version.
- Verify whether IEC 60870-5-104 bidirectional functionality is configured.
- Document whether IEC 62351-3 secure communication is enabled.
- Review vendor advisory status before concluding remediation is complete.
- Monitor for availability anomalies in affected RTU500 environments.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-184: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2026-1773 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.7 (4.0)
- Known Exploited
- No
- Published
Vector: 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
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
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——Hitachi EnergyVulnerability scoring details
Base CVSS 4.0 score
8.7HighVector: 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
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://publisher.hitachienergy.com/preview?DocumentID=8DBD000237&LanguageCode=en&DocumentPartId=&Action=LaunchCVE reference, Hitachi Energy
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Incomplete List of Disallowed Inputs
Incomplete List of Disallowed Inputs represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.