CVE-2025-53020 is a high-severity vulnerability identified in the Apache HTTP Server, specifically affecting versions from 2.4.17 up to 2.4.63. The vulnerability is categorized under CWE-401, which pertains to 'Missing Release of Memory after Effective Lifetime.' This means that the Apache HTTP Server fails to properly release allocated memory after it is no longer needed, leading to a late release or potential memory leak. Over time, this can cause the server process to consume increasing amounts of memory, potentially exhausting system resources and causing denial of service (DoS) conditions. The vulnerability is remotely exploitable without requiring authentication or user interaction, as indicated by the CVSS vector (AV:N/AC:L/PR:N/UI:N). The impact is limited to availability, with no direct confidentiality or integrity compromise reported. The issue was addressed in Apache HTTP Server version 2.4.64, and users are strongly advised to upgrade to this or later versions to mitigate the risk. No known exploits are currently reported in the wild, but the ease of exploitation and potential for service disruption make this a significant threat to affected systems.

For European organizations, this vulnerability poses a substantial risk to the availability of web services relying on Apache HTTP Server versions 2.4.17 to 2.4.63. Apache HTTP Server is widely used across Europe in both public and private sectors, including government agencies, financial institutions, healthcare providers, and critical infrastructure operators. A successful exploitation could lead to memory exhaustion, causing web servers to crash or become unresponsive, resulting in service outages. This can disrupt business operations, degrade user experience, and potentially lead to financial losses and reputational damage. Additionally, organizations with strict uptime requirements or those providing critical online services may face regulatory scrutiny if service disruptions occur. Although no confidentiality or integrity impacts are reported, the availability impact alone is significant, especially for high-traffic or mission-critical web servers.

To mitigate this vulnerability, European organizations should prioritize upgrading all affected Apache HTTP Server instances to version 2.4.64 or later, where the memory release issue has been fixed. Beyond patching, organizations should implement proactive monitoring of server memory usage to detect abnormal increases that may indicate exploitation or related issues. Employing resource limits and process isolation (e.g., using containers or dedicated virtual machines) can help contain the impact of memory leaks. Additionally, organizations should review their incident response plans to include scenarios involving denial of service due to resource exhaustion. Network-level protections such as rate limiting and web application firewalls (WAFs) may help reduce the risk of exploitation by limiting the volume of requests that could trigger memory leaks. Finally, maintaining an asset inventory to identify all Apache HTTP Server deployments is critical to ensure comprehensive remediation.