CVE-2025-53603 is a vulnerability identified in Alinto SOPE's SOGo product, specifically affecting versions from 2.0.2 through 5.12.2. The root cause is a NULL pointer dereference in the sope-core component, within the NGExtensions/NGHashMap.m source file. This occurs when a specially crafted HTTP request includes a parameter duplicated in both the query string and the POST body. The software fails to handle this scenario correctly, resulting in a NULL pointer dereference that causes the SOGo service to crash. This crash leads to a denial of service (DoS) condition, impacting the availability of the service. The vulnerability is remotely exploitable without any authentication or user interaction, increasing its risk profile. The CVSS v3.1 score is 7.5, reflecting high severity primarily due to the ease of exploitation and the impact on availability. No confidentiality or integrity impacts are noted. Although no public exploits are currently known, the vulnerability's nature suggests that attackers could disrupt email and collaboration services by repeatedly triggering the crash. The lack of a patch link indicates that remediation may require vendor updates or workarounds. Organizations using affected versions should be aware of this flaw and prepare to implement mitigations or updates once available.

The primary impact of CVE-2025-53603 is a denial of service condition caused by the SOGo service crashing upon receiving maliciously crafted requests. For European organizations, this can lead to significant disruption of email and groupware services, which are critical for daily operations, internal communications, and collaboration. In sectors such as government, finance, healthcare, and critical infrastructure, service outages can result in operational delays, loss of productivity, and potential regulatory compliance issues related to service availability. Since the vulnerability does not affect confidentiality or integrity, data breaches or unauthorized data modifications are not direct concerns. However, the availability impact can indirectly affect business continuity and trust in IT services. The ease of remote exploitation without authentication means attackers can launch DoS attacks from outside the network, potentially causing widespread service interruptions. Organizations with high dependency on Alinto SOPE SOGo for communication are particularly vulnerable, and prolonged outages could have cascading effects on other business processes and incident response capabilities.

To mitigate CVE-2025-53603, European organizations should implement the following specific measures: 1) Immediately monitor network traffic for HTTP requests containing duplicate parameters in both query strings and POST bodies, and block or filter such requests at the web application firewall (WAF) or reverse proxy level. 2) Apply strict input validation rules on the server side to reject requests with conflicting or duplicate parameters before they reach the vulnerable component. 3) Deploy rate limiting to reduce the risk of repeated exploitation attempts causing service crashes. 4) Isolate the SOGo service in a segmented network zone to limit the blast radius of potential DoS attacks. 5) Maintain up-to-date backups and ensure rapid restart procedures for the SOGo service to minimize downtime. 6) Engage with Alinto for official patches or updates addressing this vulnerability and plan for timely deployment once available. 7) Conduct regular security assessments and penetration testing focusing on input handling and denial of service vectors. 8) Educate IT staff on recognizing symptoms of this vulnerability exploitation, such as unexpected service crashes or abnormal request patterns. These targeted actions go beyond generic advice by focusing on the specific trigger mechanism and operational continuity.