CVE-2026-0401 in SonicOS
Summary
by MITRE • 02/24/2026
A post-authentication NULL Pointer Dereference vulnerability in SonicOS allows a remote attacker to crash a firewall.
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Analysis
by VulDB Data Team • 02/28/2026
The vulnerability identified as CVE-2026-0401 represents a critical post-authentication NULL pointer dereference flaw within SonicOS firmware, which powers SonicWall firewalls widely deployed in enterprise environments. This vulnerability specifically affects the authentication flow where an authenticated attacker can manipulate certain parameters to trigger a NULL pointer dereference condition. The flaw exists in the firmware processing logic that handles specific administrative requests after successful authentication, creating a path for remote exploitation that can lead to complete service disruption.
The technical implementation of this vulnerability stems from insufficient input validation within the SonicOS authentication handler module. When an authenticated user submits crafted requests containing malformed data structures or missing parameters, the system attempts to dereference a NULL pointer during the processing of these requests. This occurs because the firmware code does not properly validate whether certain pointers have been initialized before attempting to access their contents. The vulnerability is classified under CWE-476 as a NULL pointer dereference, which is a common class of software defects that can result in application crashes or potentially more severe consequences when exploited in specific contexts.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be leveraged by remote attackers to perform denial-of-service attacks against firewall infrastructure. When successfully exploited, the NULL pointer dereference causes the SonicWall firewall to crash and restart, potentially leading to network outages that can affect critical business operations. The vulnerability's post-authentication requirement means that attackers must first obtain valid credentials through other means such as credential stuffing, password spraying, or successful exploitation of other vulnerabilities, making the attack chain more complex but still feasible in environments where authentication credentials may be compromised. This weakness directly maps to the ATT&CK technique T1110 for credential access and T1499 for endpoint denial of service.
Mitigation strategies for CVE-2026-0401 should prioritize immediate firmware updates from SonicWall to address the root cause of the NULL pointer dereference. Organizations should also implement network segmentation and access controls to limit the potential impact of authenticated attacks, ensuring that only authorized personnel have administrative access to firewall systems. Additional defensive measures include monitoring for unusual authentication patterns, implementing intrusion detection systems that can identify malformed requests, and maintaining robust backup and recovery procedures to minimize downtime during potential exploitation events. The vulnerability underscores the importance of proper input validation and error handling in network security devices, particularly those operating in critical infrastructure environments where availability is paramount to overall network security posture.