What is the CVSS score of CVE-2026-2459?

CVE-2026-2459 has a CVSS 4.0 base score of 7.4 (High). CVSS vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N. EPSS exploitation probability: 0.0%.

How to fix or mitigate CVE-2026-2459?

Within 24 hours: Identify all REB500 instances in your environment and document current Installer role users. Within 7 days: Implement access controls to restrict Installer role scope, enable enhanced logging for file access/modifications, and audit recent directory changes. Within 30 days: Evaluate alternative products or isolated deployment architectures; establish a vendor communication channel to track patch availability and apply immediately upon release.

Reb500 Firmware CVE-2026-2459

HIGH

Privilege Defined With Unsafe Actions (CWE-267)

2026-02-24 cybersecurity@hitachienergy.com

Information Disclosure Reb500 Firmware Hitachienergy

7.4

CVSS 4.0 · NVD

View

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

Access

Authenticate as Installer role user
Exploit

Send directory access request
Execution

Bypass authorization checks
Impact

Alter unauthorized directory contents

Vulnerability Assessment

Weakness	CWE CWE-267 OWASP Top 10:2025 A06:2021 - Vulnerable and Outdated Components ASVS 5.0 V8 - Authorization Privilege defined with unsafe actions
Exploitation Conditions	REB500 device with authenticated Installer role account. Attacker must possess valid Installer credentials to access the vulnerable directory modification functionality. Installer role has insufficient access control restrictions on directory operations.
Impact	CVSS 8.1 (HIGH). Attack vector: Network. Complexity: Low. Privileges required: Low. User interaction: None. Exploitation requires authentication.
Exploit ScenarioDerived	An attacker (requires authentication) could exploit this vulnerability to compromise the affected system.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).

No patch listed yet 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

Authenticated users with Installer role in REB500 firmware can bypass directory access controls to read and modify files outside their authorized scope. This privilege escalation affects systems where installer accounts are provisioned, enabling unauthorized data access and manipulation. No patch is currently available.

Earlier versions of this analysis (1)

v1 Mar 12, 2026 - 21:55 CVSS 7.4

A vulnerability exists in REB500 for an authenticated user with Installer role to access and alter the contents of directories that the role is not authorized to do so. [CVSS 8.1 HIGH]

RemediationAI

Monitor vendor advisories for a patch. Restrict network access to the affected service where possible.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

Affects Reb500 Firmware. A vulnerability exists in REB500 for an authenticated user with Installer role to access and alter the contents of directories that the role is not authorized to do so.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 7.4 HIGH

CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Attack Requirements

Present

Privileges Required

High

User Interaction

None

Vulnerable system: Confidentiality

High

Vulnerable system: Integrity

High

Vulnerable system: Availability

None

Subsequent system: Confidentiality

None

Subsequent system: Integrity

None

Subsequent system: Availability

None

DescriptionCVE.org

A vulnerability exists in REB500 for an authenticated user with Installer role to access and alter the contents of directories that the role is not authorized to do so.

Executive ViewAI

Why It Matters

A privilege escalation vulnerability in REB500 allows authenticated users with Installer role to access and modify files and directories beyond their authorization level, potentially compromising system integrity and sensitive data. This poses a significant risk to organizations relying on REB500 for critical operations, as internal threat actors or compromised accounts could escalate privileges without detection.

Business Impact: High

Compensating Controls

Disable Installer role functionality where operationally feasible; implement network segmentation to restrict REB500 access to trusted users only; deploy file integrity monitoring (FIM) to detect unauthorized directory modifications; enforce principle of least privilege through additional access control layers outside REB500; increase audit logging and monitoring for suspicious Installer role activity; consider running REB500 in a restricted container or VM environment.

Threat Intelligence Overview

EPSS Score

0.0%

Top 92% exploitable

Data Quality

3 sources

Confidence: Low

NVD

CVE.org

EPSS

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity HIGH

CISA KEV No

Public POC No

EPSS 0.0%

Patch available No

Active threat No

Deciding rule

HIGH severity (CVSS 7.0-8.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Scheduled

Exploitation· derived

None

System Exposure· derived

Open

Automatable· derived

Human Impact

High

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +37

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Information Disclosure MEDIUM

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.