CVE-2026-31851 in Nebula 300+
Summary
by MITRE • 03/23/2026
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.
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Analysis
by VulDB Data Team • 03/27/2026
The vulnerability identified as CVE-2026-31851 affects the Nexxt Solutions Nebula 300+ security appliance firmware version 12.01.01.37 and earlier, presenting a critical weakness in authentication security controls. This flaw represents a fundamental failure in access control implementation that directly violates established security best practices and industry standards. The absence of rate limiting and account lockout mechanisms creates an environment where malicious actors can conduct unrestricted brute-force attacks against administrative interfaces, fundamentally undermining the device's security posture and potentially compromising the entire network infrastructure it protects.
The technical nature of this vulnerability stems from the firmware's complete omission of authentication throttling mechanisms that are essential for preventing automated credential guessing attacks. According to CWE-307, this represents a weakness in the design of authentication systems that fails to implement proper rate limiting controls. The lack of account lockout functionality means that attackers can continuously attempt to authenticate using various credential combinations without facing any system-imposed restrictions or delays. This flaw directly enables credential stuffing and brute-force attacks, where attackers can systematically test thousands or millions of username and password combinations against the device's authentication interfaces without any defensive mechanisms to slow down or block these attempts.
The operational impact of this vulnerability extends beyond simple credential compromise, as it creates a persistent threat vector that can be exploited by adversaries with minimal technical expertise. Attackers can leverage automated tools to rapidly test common administrative credentials, potentially gaining unauthorized access to the device's management interfaces and subsequently compromising the entire network security infrastructure. This vulnerability aligns with ATT&CK technique T1110.003, which describes credential stuffing and brute force attacks, demonstrating how the absence of proper authentication controls enables attackers to systematically compromise system access. The implications are particularly severe given that the Nebula 300+ appliance serves as a security gateway, meaning unauthorized access could provide attackers with privileged network access and control over critical security functions.
Organizations utilizing affected firmware versions face significant risks including potential network infiltration, unauthorized administrative access, and complete compromise of the security appliance's protective capabilities. The vulnerability creates a persistent backdoor that can be exploited by attackers with minimal resources, making it an attractive target for both opportunistic and targeted attacks. Security professionals should immediately implement mitigations including network segmentation, firewall rules to restrict access to management interfaces, and deployment of intrusion detection systems to monitor for authentication attempts. Additionally, the firmware should be updated to the latest version as soon as available, though organizations should also consider implementing additional authentication controls such as multi-factor authentication and IP-based access restrictions to provide defense in depth against this specific vulnerability.