CVE-2026-31847

Hidden Functionality Enables Remote Telnet Activation via /goform/setSysTools in Nexxt Nebula 300+

CVSS 8.5 HIGHEPSS 0.4%CWE-912

Vexday Risk Score

21Low

SSVC decision (CISA)

Track

No exploitation signal → monitor

CVSS 8.5EPSS 0.4%KEV nãoPoC —Patch —

Lifecycle

23 Mar 2026Published on NVD

Recommendation: Monitor — no exploitation signal at the moment.

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.

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

Affected products

Nexxt Solutions · Nebula 300+

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References

https://nexxt-connectivity-frontend.s3.amazonaws.com/media/docs/Nebula300+_v12.01.01.37.zip https://www.nexxtsolutions.com/connectivity/internal-products/ARN02304U6/