Nexxt Solutions Nebula 300+ up to 12.01.01.37 Telnet Service /goform/setSysTools backdoor

Summaryinfo

A vulnerability classified as critical was found in Nexxt Solutions Nebula 300+ up to 12.01.01.37. Affected by this vulnerability is an unknown functionality of the file /goform/setSysTools of the component Telnet Service. The manipulation results in backdoor. This vulnerability is identified as CVE-2026-31847. The attack can only be performed from the local network. There is not any exploit available.

Detailsinfo

A vulnerability, which was classified as critical, was found in Nexxt Solutions Nebula 300+ up to 12.01.01.37. Affected is an unknown function of the file /goform/setSysTools of the component Telnet Service. The manipulation with an unknown input leads to a backdoor vulnerability. CWE is classifying the issue as CWE-912. 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. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

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. This exposes a privileged diagnostic interface that is not intended for external access and can be used to interact with the underlying system.

The weakness was released by Angel Barre. The advisory is available at nexxtsolutions.com. This vulnerability is traded as CVE-2026-31847 since 03/09/2026. The exploitability is told to be easy. The attack needs to approached within the local network. The exploitation doesn't require any form of authentication. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 03/27/2026). This vulnerability is assigned to T1588.001 by the MITRE ATT&CK project.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Vendor

• Nexxt Solutions

Name

• Nebula 300+

Version

• 12.01.01.0
• 12.01.01.1
• 12.01.01.2
• 12.01.01.3
• 12.01.01.4
• 12.01.01.5
• 12.01.01.6
• 12.01.01.7
• 12.01.01.8
• 12.01.01.9
• 12.01.01.10
• 12.01.01.11
• 12.01.01.12
• 12.01.01.13
• 12.01.01.14
• 12.01.01.15
• 12.01.01.16
• 12.01.01.17
• 12.01.01.18
• 12.01.01.19
• 12.01.01.20
• 12.01.01.21
• 12.01.01.22
• 12.01.01.23
• 12.01.01.24
• 12.01.01.25
• 12.01.01.26
• 12.01.01.27
• 12.01.01.28
• 12.01.01.29
• 12.01.01.30
• 12.01.01.31
• 12.01.01.32
• 12.01.01.33
• 12.01.01.34
• 12.01.01.35
• 12.01.01.36
• 12.01.01.37

CPE 2.3info

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If you want to get best quality of vulnerability data, you may have to visit VulDB.

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