CVE-2025-55128 identifies a vulnerability in Revive Adserver version 6, a widely used open-source ad serving platform. The flaw resides in the userlog-index.php script, which handles the display of user logs within the admin interface. Specifically, the vulnerability allows an authenticated administrator to specify an arbitrarily large number of items per page when requesting user log data. This unchecked parameter leads to uncontrolled resource consumption, as the server attempts to process and render an excessive volume of data in a single request. The consequence is a denial of service condition, where server performance degrades or the service becomes entirely unavailable due to resource exhaustion such as CPU, memory, or database load. The vulnerability is classified under CWE-400 (Uncontrolled Resource Consumption). The attack vector requires network access (remote) and privileges of an authenticated admin user, with no user interaction needed beyond that. The CVSS v3.0 base score is 6.5, indicating a medium severity level, primarily due to the requirement for admin privileges and the impact being limited to availability without affecting confidentiality or integrity. No patches or known exploits are currently available or reported, but the vulnerability is publicly disclosed and should be addressed promptly to prevent potential exploitation.

For European organizations, the primary impact of this vulnerability is the risk of denial of service affecting the availability of the Revive Adserver platform. Organizations relying on this platform for digital advertising campaigns could experience service outages or degraded performance, disrupting ad delivery and potentially causing financial losses and reputational damage. Since the vulnerability requires admin access, the risk is heightened if admin credentials are compromised or if insider threats exist. The disruption could also affect third-party advertisers and partners relying on the ad server's availability. Given the importance of digital marketing in Europe's economy, especially in countries with large advertising markets, this vulnerability could have a tangible operational impact. However, the absence of confidentiality or integrity impact limits the scope of damage to service availability only.

1. Restrict and monitor admin access strictly, employing strong authentication mechanisms such as multi-factor authentication (MFA) to reduce the risk of credential compromise. 2. Implement rate limiting or input validation on the userlog-index.php page to cap the maximum number of items per page, preventing excessive resource consumption. 3. Regularly audit and monitor server performance and logs for unusual spikes in resource usage or large requests targeting the admin interface. 4. If possible, isolate the ad server environment to limit the impact of potential DoS conditions on other critical systems. 5. Stay updated with Revive Adserver vendor announcements for patches or official fixes and apply them promptly once available. 6. Consider implementing web application firewalls (WAF) rules to detect and block abnormal request patterns targeting the admin interface. 7. Educate administrators on the risks of this vulnerability and encourage best practices for credential security and session management.