CVE-2026-62673: Grav: .htaccess file extension rules bypass via case variation on case-insensitive filesystems

The default .htaccess shipped with Grav (and the reference webserver-configs/htaccess.txt) contains security rules that block direct HTTP access to sensitive file types (.yaml, .yml, .php, .json, .twig, etc.) under user/ and system/vendor/ directories. However, these rules lack the [NC] (No Case) flag, making them case-sensitive. On case-insensitive filesystems (Windows/NTFS, macOS/HFS+, or Linux with Docker volumes mounted from Windows/macOS), an attacker can bypass these rules by requesting files with uppercase extensions (e.g., .YAML, .PHP, .JSON).