CVE-2025-53603 is a vulnerability identified in Alinto SOPE's SOGo groupware software versions 2.0.2 through 5.12.2. The root cause is a NULL pointer dereference in the sope-core component, specifically within NGExtensions/NGHashMap.m, triggered when an HTTP request contains a parameter duplicated both in the query string and the POST body. This malformed request causes the software to dereference a NULL pointer, leading to a crash of the SOGo service, effectively resulting in a denial-of-service (DoS) condition. The vulnerability does not affect confidentiality or integrity but severely impacts availability. The flaw can be exploited remotely without any authentication or user interaction, making it accessible to unauthenticated attackers over the network. Although no known exploits are currently reported in the wild, the vulnerability's nature and ease of exploitation make it a significant risk. The CVSS v3.1 score of 7.5 reflects a high severity, primarily due to the network attack vector, lack of required privileges, and the complete loss of service availability. The absence of vendor patches at the time of publication necessitates immediate attention to alternative mitigation strategies.

For European organizations, the primary impact of CVE-2025-53603 is the potential for denial-of-service attacks against critical groupware and collaboration infrastructure running Alinto SOPE's SOGo software. Such outages can disrupt internal communications, scheduling, and email services, leading to operational downtime and productivity losses. Sectors relying heavily on these services, including government agencies, financial institutions, healthcare providers, and large enterprises, may experience significant operational challenges. The vulnerability does not expose sensitive data or allow unauthorized data modification, but the availability impact can indirectly affect business continuity and service level agreements. Additionally, repeated exploitation attempts could increase network noise and complicate incident response efforts. Given the remote and unauthenticated nature of the exploit, attackers can easily target exposed SOGo instances, increasing the risk of widespread disruption across European organizations using this software.

1. Apply official patches from Alinto as soon as they become available to address the NULL pointer dereference directly. 2. Until patches are released, implement strict input validation and filtering at the web application firewall (WAF) or reverse proxy level to detect and block HTTP requests containing duplicate parameters in both query strings and POST bodies. 3. Monitor network traffic and application logs for anomalous requests exhibiting this pattern to identify potential exploitation attempts early. 4. Employ rate limiting and IP reputation-based blocking to reduce the risk of automated or repeated exploitation attempts. 5. Consider deploying redundancy and failover mechanisms for SOGo services to minimize downtime in case of successful exploitation. 6. Conduct regular security assessments and penetration testing focused on input validation weaknesses in web-facing services. 7. Educate IT and security teams about this vulnerability to ensure rapid detection and response.