Nebula 300+: Hidden Functionality
CVE-2026-31847 is a high-severity hidden functionality vulnerability in Nebula 300+ from Nexxt Solutions, with a CVSS 3.1 base score of 8.8 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 Nebula 300+ versions: <= 12.01.01.37 through Nebula300+_v12.01.01.37. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.42% 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 Nebula 300+ you run against the affected versions below, and install the vendor's latest release.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Nexxt Solutions | Nebula 300+ | <= 12.01.01.37 through Nebula300+_v12.01.01.37 | Not stated |
| Nexxtsolutions | Nebula300plus Firmware | 12.01.01.37 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
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 8.5 | High | CNA |
| CVSS 3.1 | 8.8 | High | NVD |
Official description
Hidden functionality in the /goform/setSysTools endpoint in Nexxt Solutions Nebula 300+ firmware through version 12.01.01.37 allows remote enablement of a Telnet service. By sending a crafted POST request with parameters such as telnetManageEn=true and telnetPwd, an authenticated attacker can activate a Telnet service on port 23.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Hidden Functionality
The product contains functionality that is not documented, not part of the specification, and not accessible through an interface or command sequence that is obvious to the product's users or administrators.
How developers prevent this class of flaw
- Always verify the integrity of the product that is being installed.
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 references
Other vulnerabilities in Nebula 300+
- 9.8 Critical severity
- 9.8 Critical severity
Recent Hidden Functionality vulnerabilities
- 10.0 Critical severity
- 7.2 High severity
- 9.5 Critical severity
- 8.6 High severity
- 7.2 High severity
- 8.1 High severity
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