CVE-2023-28461 is a critical security vulnerability affecting Array Networks Array AG Series and vxAG SSL VPN appliances running firmware version 9.4.0.481 and earlier. This vulnerability allows an unauthenticated remote attacker to execute arbitrary code on the SSL VPN gateway. The attack vector involves sending a specially crafted HTTP request containing a 'flags' attribute in the header, which enables the attacker to browse the underlying filesystem of the VPN gateway without any authentication. Following this reconnaissance, the attacker can exploit a vulnerable URL endpoint to achieve remote code execution (RCE). The vulnerability stems from improper access control (CWE-306), allowing unauthorized access to sensitive system functions. The CVSS v3.1 base score is 9.8, indicating a critical severity with network attack vector, low attack complexity, no privileges required, and no user interaction needed. The impact includes full compromise of confidentiality, integrity, and availability of the affected device, potentially allowing attackers to pivot into internal networks, intercept or manipulate VPN traffic, and disrupt remote access services. As of the vendor advisory dated March 9, 2023, a patch was forthcoming but not yet available at the time of this report. No known exploits in the wild have been reported yet, but the ease of exploitation and critical impact make this a high-priority threat.

For European organizations, this vulnerability poses a severe risk to secure remote access infrastructure. SSL VPN gateways are critical for enabling remote workforce connectivity and protecting internal networks. Exploitation could lead to full compromise of the VPN appliance, allowing attackers to access internal corporate resources, intercept sensitive communications, and deploy further malware or ransomware. This could disrupt business continuity, lead to data breaches involving personal and corporate data protected under GDPR, and damage organizational reputation. Sectors such as finance, healthcare, government, and critical infrastructure in Europe are particularly vulnerable due to their reliance on secure VPN access and the high value of their data. Additionally, the lack of authentication requirement increases the attack surface, potentially enabling widespread scanning and exploitation attempts from external threat actors.

1. Immediately restrict network access to the management interfaces of Array AG Series and vxAG appliances using firewall rules or network segmentation to limit exposure to trusted IP addresses only. 2. Monitor VPN gateway logs and network traffic for unusual HTTP requests containing suspicious headers or access patterns indicative of exploitation attempts. 3. Apply vendor patches as soon as they become available; prioritize patching in all environments, especially production and internet-facing devices. 4. If patching is delayed, consider temporary mitigations such as disabling vulnerable services or applying web application firewall (WAF) rules to block malicious HTTP headers or URLs. 5. Conduct thorough audits of VPN appliance configurations and ensure strong authentication and access controls are in place for administrative interfaces. 6. Educate security teams to recognize indicators of compromise related to this vulnerability and prepare incident response plans for potential exploitation. 7. Engage with vendors and security communities for updates and threat intelligence related to this CVE.