CVE-2025-30188 is a vulnerability identified in Open-Xchange GmbH's OX App Suite, a widely used collaboration and communication platform. The issue arises from uncontrolled resource consumption triggered by API requests that add large amounts of data to internal caches. These caches are designed to improve performance by storing frequently accessed data; however, when flooded with excessive data, they may evict essential cached information required for the web frontend's normal operation. This eviction leads to unavailability of the affected component, effectively causing a denial-of-service (DoS) condition. The vulnerability is remotely exploitable without any authentication or user interaction, increasing its risk profile. The CVSS 3.1 base score of 7.5 reflects the high impact on availability (A:H) with no impact on confidentiality or integrity, and low attack complexity (AC:L). Although no public exploits have been reported yet, the potential for disruption is significant, especially in environments heavily reliant on OX App Suite for daily operations. The affected versions are not explicitly detailed beyond '0', suggesting early or all versions prior to patching may be vulnerable. The vendor has released updates and patches to address this issue, emphasizing the importance of timely remediation.

For European organizations, the primary impact of CVE-2025-30188 is service unavailability due to denial-of-service conditions caused by cache exhaustion. Organizations relying on OX App Suite for email, calendaring, and collaboration may experience significant operational disruptions, affecting productivity and communication. This can be particularly damaging for sectors such as government, finance, healthcare, and education, where continuous availability of communication platforms is critical. The lack of confidentiality or integrity impact limits data breach concerns, but the availability impact alone can lead to financial losses, reputational damage, and compliance issues under regulations like GDPR if service outages affect user data access. Additionally, the ease of exploitation without authentication means attackers can launch attacks from external networks, increasing the threat surface. The absence of known public exploits currently reduces immediate risk but does not eliminate the potential for future exploitation. Organizations with large user bases or high transaction volumes on OX App Suite are more vulnerable to large-scale disruptions.

To mitigate CVE-2025-30188, European organizations should immediately deploy the vendor-provided patches and updates for OX App Suite. Beyond patching, organizations should implement strict rate limiting and throttling on API endpoints to prevent excessive cache data injection. Monitoring cache utilization metrics and setting alerts for abnormal cache growth can help detect early signs of exploitation. Network-level protections such as Web Application Firewalls (WAFs) should be configured to identify and block suspicious API request patterns. Additionally, segmenting the OX App Suite infrastructure and applying resource quotas can limit the impact of resource exhaustion. Regularly reviewing and updating incident response plans to include scenarios involving denial-of-service via resource exhaustion will improve preparedness. Finally, maintaining up-to-date inventories of affected systems and ensuring that all instances of OX App Suite are accounted for and patched is critical to comprehensive risk reduction.