CVE-2026-0401 is a NULL Pointer Dereference vulnerability classified under CWE-476 found in SonicWall's SonicOS firewall operating system. This vulnerability exists in multiple versions of SonicOS, specifically 7.0.1-5169 and older, 7.3.1-7013 and older, and 8.1.0-8017 and older. The flaw is triggered post-authentication, meaning an attacker must have valid credentials to exploit it. Upon exploitation, the attacker can cause the firewall to crash, resulting in a denial of service (DoS) condition. The vulnerability does not allow for data disclosure or modification but impacts the availability of the firewall, potentially disrupting network security enforcement and connectivity. The CVSS v3.1 score is 4.9 (medium), with an attack vector of network, low attack complexity, requiring high privileges, no user interaction, and unchanged scope. No public exploits or patches have been reported at the time of publication. The vulnerability likely arises from improper handling of null pointers in the code, leading to a crash when the system attempts to dereference a null pointer during certain operations after authentication.

The primary impact of CVE-2026-0401 is a denial of service against SonicWall firewalls running affected SonicOS versions. This can lead to temporary loss of firewall protection, network segmentation, and potential exposure of internal networks to threats. Organizations relying on these firewalls for perimeter defense, VPN termination, or internal segmentation may experience service outages and increased risk during the downtime. Critical infrastructure, enterprises, and service providers using SonicWall devices could face operational disruptions. Since exploitation requires authentication, the risk is somewhat mitigated by credential protection, but insider threats or compromised credentials could enable attacks. The lack of integrity or confidentiality impact limits the scope to availability, but availability loss in security appliances can have cascading effects on organizational security posture and business continuity.

Organizations should immediately review and restrict access to SonicWall management interfaces to trusted personnel only, employing strong authentication mechanisms such as multi-factor authentication to reduce the risk of credential compromise. Network segmentation should be enforced to limit access to firewall management ports. Monitoring and logging of administrative access attempts should be enhanced to detect suspicious activity. Since no patches are currently linked, organizations should stay alert for official SonicWall security advisories and apply updates promptly once available. Temporary mitigations may include rebooting affected devices if crashes occur and implementing redundant firewall architectures to maintain availability during incidents. Conducting regular credential audits and enforcing least privilege principles for firewall administrators will further reduce exploitation risk.