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CVE-2026-31851: Nexxtsolutions Nebula300plus Firmware Security Vulnerability (CVSS 7.7)

CVE-2026-31851 is a high severity security vulnerability in Nexxtsolutions Nebula300plus Firmware with a CVSS score of 7.7. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.

Last updated: Jun 17, 2026

Quick answer

Direct answer

CVE-2026-31851 is a high severity security vulnerability in Nexxtsolutions Nebula300plus Firmware with a CVSS score of 7.7. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.

Risk scores

CVSS base score
7.7HIGH
EPSS probability
0.67%
Higher than 51 percent of all CVEs
CISA KEV
Not listed
CVSS metricWhat it means
Attack vector (AV:A)Adjacent network
Attack complexity (AC:H)High complexity
Attack requirements (AT:N)No attack requirements
Privileges required (PR:N)No privileges required
User interaction (UI:N)No user interaction
Confidentiality (VC:H)High confidentiality impact
Integrity (VI:H)High integrity impact
Availability (VA:H)High availability impact

CVSS:4.0/AV:A/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

About Nexxtsolutions Nebula300plus Firmware

CVE-2026-31851 affects Nexxtsolutions Nebula300plus Firmware, a product from Nexxtsolutions. Before acting, confirm where Nexxtsolutions Nebula300plus Firmware runs in your estate, who owns it and whether it is reachable from the internet, because exposure decides real risk more than the score alone.

What the flaw is

In plain terms: Nexxt Solutions Nebula 300+ firmware through version 12.01.01.37 does not implement rate limiting or account lockout mechanisms on authentication interfaces. An attacker can perform unlimited authentication attempts against endpoints that rely on credential validation, enabling brute-force attacks to guess administrative credentials without restriction.

Based on its CVSS vector, the flaw needs local or adjacent access, needs no login, and needs no user interaction. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.

Affected versions and timeline

FieldDetail
ProductNexxtsolutions Nebula300plus Firmware
Affected versionsNebula300plus Firmware up to and including 12.01.01.37
PublishedMar 23, 2026
Last modifiedJun 17, 2026
Added to CISA KEVNot listed
Assigning CNA309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c

How to detect it

  • Inventory every instance of Nexxtsolutions Nebula300plus Firmware and record the running version against the affected range above.
  • Check external attack surface scans for internet facing instances of the component.
  • Review logs on affected systems for unusual requests, errors or new processes around the vulnerable function.
  • Confirm with an authenticated vulnerability scan once your scanner has a check for this CVE.

How to fix it

  • Apply the fixed version of Nexxtsolutions Nebula300plus Firmware named in the vendor advisory.
  • If patching must wait, restrict network access to the affected service and put it behind authentication or a web application firewall rule.
  • Rescan after the change to prove the exposure is gone, then close the ticket.

CTEM action plan

CTEM stageWhat to do for this CVE
ScopeAdd every business service that depends on Nexxtsolutions Nebula300plus Firmware to the current CTEM cycle.
DiscoverFind all instances, including shadow and cloud deployments, and record versions and exposure.
PrioritizeRank using EPSS and CVSS together with asset exposure and business impact.
ValidateConfirm the flaw is reachable and exploitable in your environment and that compensating controls work.
MobilizeAssign the fix to the asset owner with a due date matched to the priority, then verify closure.

CWE References

Technical References

Frequently asked questions

CVE-2026-31851 is a high severity security vulnerability in Nexxtsolutions Nebula300plus Firmware with a CVSS score of 7.7. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.

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