Microsoft has addressed growing user concerns regarding significant resource consumption in Windows 11 version 25H2 and Windows Server 2025. Technical documentation confirms that the November 2025 security update introduced a cryptographic layer to the Common Log File System driver to block persistent privilege escalation exploits.
This security enhancement requires the system to generate a Hash-based Message Authentication Code for every logfile interaction, a process that has effectively doubled the operational time for writing new records.
The implementation involves merging log data with a unique system key to ensure file integrity and prevent unauthorized tampering. This constant verification process has led to a spike in input and output operations, causing noticeable latency during file creation and access.
Additionally, the new security codes demand extra storage space, with 4GB containers now requiring an additional 2.1 megabytes of disk capacity. Microsoft has launched a 90 day grace period during which the system will automatically update files to this new standard before entering a mandatory enforcement phase in early 2026.
Government IT departments and private sector administrators are being urged to take immediate action to maintain system stability. Stakeholders must conduct thorough audits of all applications utilizing the logging subsystem and use administrative command line tools to authenticate files that remain unopened. This proactive approach is essential to prevent widespread application failures once the system begins rejecting unverified logfiles later this year.
