An integer overflow in the Apache HTTP Server ACME renewal process can trigger a denial of service or resource exhaustion by forcing repeated, rapid certificate renewal attempts.

This vulnerability involves an integer overflow (CWE-190) occurring during failed ACME certificate renewals, which causes the system to ignore backoff timers after approximately 30 days of persistent failures. The flaw is unauthenticated, as the renewal process is typically handled automatically by the server daemon.

The exploitation of this vulnerability can lead to significant resource exhaustion on the server, potentially resulting in service degradation or localized denial of service conditions. While the CVSS score of 7.5 indicates a high severity primarily due to the impact on availability, the risk is compounded by the automated nature of the renewal process, which could lead to unexpected operational instability in production environments.

Immediate Action: Upgrade to Apache HTTP Server version 2.4.66 or later to incorporate the necessary logic fixes for the ACME renewal backoff mechanism.

Proactive Monitoring: Review server logs for anomalous patterns of repeated failed ACME certificate renewal attempts or unusual spikes in process activity related to the renewal module.

Compensating Controls: If immediate patching is not feasible, consider implementing rate-limiting at the network or application layer for ACME-related traffic or temporarily disabling the automated ACME renewal feature if certificate management can be handled via alternative methods.

Public Exploit Available: Unknown

Given the potential for service disruption and the ease of triggering the condition once the failure threshold is reached, administrators should prioritize updating to version 2.4.66. Patching this vulnerability is essential to ensuring the long-term stability of automated certificate management processes and preventing unnecessary resource consumption.