Grav before 2.0.4 ships a default .htaccess (and reference webserver-configs/htaccess.txt) whose rules blocking access to sensitive file types (.yaml, .php, .json, etc.) lack the [NC] flag, making extension matching case-sensitive. On case-insensitive filesystems (Windows/NTFS, macOS/HFS+, or Docker volume mounts), an unauthenticated attacker can request these files with uppercase or mixed-case extensions (e.g., .YAML, .PHP) to bypass the restrictions and read sensitive configuration files that may contain API keys and credentials.
Exploitability
AV:NAC:LAT:NPR:NUI:NVulnerable System
VC:HVI:NVA:NSubsequent System
SC:NSI:NSA:N8.7/CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:NOther