Relion REB500: Privilege Defined With Unsafe Actions
CVE-2026-2459 is a high-severity privilege defined with unsafe actions vulnerability in Relion REB500 from Hitachi Energy, with a CVSS 3.1 base score of 8.1 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. Affected Relion REB500 versions: 8.0.0.0 through 8.3.3.0. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.37% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of Relion REB500 you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on publisher.hitachienergy.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Hitachi Energy | Relion REB500 | 8.0.0.0 through 8.3.3.0 | Not stated |
| Hitachienergy | Reb500 Firmware | 8.3.3.0 and earlier | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 7.4 | High | CNA (hitachienergy.com) |
| CVSS 3.1 | 8.1 | High | NVD |
Official description
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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Privilege Defined With Unsafe Actions
A particular privilege, role, capability, or right can be used to perform unsafe actions that were not intended, even when it is assigned to the correct entity.
How developers prevent this class of flaw
- Very carefully manage the setting, management, and handling of privileges. Explicitly manage trust zones in the software.
- Run your code using the lowest privileges that are required to accomplish the necessary tasks. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.
More Privilege Defined With Unsafe Actions vulnerabilities (CWE-267)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other vulnerabilities in Relion REB500
- 8.1 High severity
Recent Privilege Defined With Unsafe Actions vulnerabilities
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
- 8.2 High severity
- 8.2 High severity
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