Nginx 403 Forbidden — Access Denied

WebServerErrors Nginx Reconnaissance / Misconfiguration

What This Means

Troubleshoot Nginx 403 Forbidden errors. Detect unauthorized access attempts, directory listing exposure, and misconfigured permissions on your Nginx web server.

Example Log

203.0.113.55 - - [08/Mar/2026:15:22:41 +0000] "GET /admin/.env HTTP/1.1" 403 162 "-" "python-requests/2.28.0"

Indicators of Suspicious Activity

403 responses on sensitive paths (.env, .git, .htpasswd, admin panels)
Requests from automated scanning tools (python-requests, curl, nikto)
Multiple 403 responses from a single IP in rapid succession
Attempts to access hidden files and directories (paths starting with .)
403 on directory requests indicating autoindex is properly disabled
Requests with path traversal patterns receiving 403 responses

How to Investigate

Review the Nginx error log for the specific denial reason
Check file and directory permissions on the target path
Verify Nginx location block configurations for the affected paths
Correlate the source IP with threat intelligence databases
Check if the same IP has generated other error codes (404, 401)
Review the access log for successful requests from the same IP

Recommended Mitigations

Configure deny rules for sensitive file patterns in Nginx configuration
Use location blocks to restrict access to admin paths by IP
Ensure autoindex is set to off for all server blocks
Return generic error pages without server version information
Deploy fail2ban to automatically block IPs generating excessive 403s
Regularly audit Nginx configuration for accidentally exposed paths

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Related Log Types

Related Attack Patterns

Frequently Asked Questions

What causes Nginx 403 Forbidden? ▼

Nginx returns 403 when the client is denied access to a resource. Common causes include incorrect file permissions, missing index file with autoindex off, deny rules in the location block, and SELinux restrictions.

How do I fix Nginx 403 for legitimate users? ▼

Check file ownership (should be readable by the Nginx worker user), verify the location block allows GET requests, ensure an index file exists if autoindex is off, and check SELinux contexts with ls -Z.

How can I hide the Nginx version in error pages? ▼

Add server_tokens off; in the http block of your Nginx configuration to prevent the server version from appearing in error pages and response headers.