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

Summary

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).

Affected Versions

• Grav 2.0.1 (latest stable as of June 2026) — confirmed
• Grav 1.7.x — likely affected (same .htaccess rules)
• All versions shipping the current webserver-configs/htaccess.txt

Affected Component

File: .htaccess (root of Grav installation) Reference: webserver-configs/htaccess.txt

Affected Rules (lines 68, 70, 72)

# Line 68 — system/vendor file types
RewriteRule ^(system|vendor)/(.*)\.(txt|xml|md|html|htm|shtml|shtm|json|yaml|yml|php|php2|php3|php4|php5|phar|phtml|pl|py|cgi|twig|sh|bat)$ error [F]

# Line 70 — user file types
RewriteRule ^(user)/(.*)\.(txt|md|json|yaml|yml|php|php2|php3|php4|php5|phar|phtml|pl|py|cgi|twig|sh|bat)$ error [F]

# Line 72 — .md files globally
RewriteRule \.md$ error [F]

All three rules use [F] without [NC], making the extension match case-sensitive.

Steps to Reproduce

1. Install Grav on a system with a case-insensitive filesystem:

   • Windows (native WAMP/XAMPP)
   • macOS (default HFS+)
   • Docker on Windows/macOS with volume mounts (e.g., ./data:/var/www/html)

2. Create or use any plugin that stores sensitive data in its YAML config (e.g., API keys):

   user/plugins/my-plugin/my-plugin.yaml
   

3. Request the file with a case-varied extension:

   GET /user/plugins/my-plugin/my-plugin.YAML HTTP/1.1
   

4. Expected: HTTP 403 Forbidden

5. Actual: HTTP 200 OK — full file contents returned, including any API keys or sensitive configuration