CVE-2025-30207 Overview
CVE-2025-30207 is a path traversal vulnerability affecting Kirby, an open-source content management system. The vulnerability exists in Kirby setups that use PHP's built-in server, which is commonly used during local development. A missing path traversal check allows attackers to enumerate files on the server that are accessible to the PHP process, including files outside of the Kirby installation directory.
Critical Impact
Attackers can determine whether arbitrary files exist on the server through response timing differences, potentially revealing sensitive file structure information. While file contents are not directly exposed, the ability to enumerate files on a system can aid reconnaissance for further attacks.
Affected Products
- Kirby versions prior to 3.9.8.3
- Kirby versions prior to 3.10.1.2
- Kirby versions prior to 4.7.1
Discovery Timeline
- 2025-05-13 - CVE CVE-2025-30207 published to NVD
- 2025-08-26 - Last updated in NVD database
Technical Details for CVE-2025-30207
Vulnerability Analysis
This path traversal vulnerability (CWE-22) affects Kirby CMS installations that utilize PHP's built-in development server. The security flaw stems from insufficient validation in the router component, which failed to properly verify that requested files reside within the document root directory.
When processing requests, the vulnerable implementation delegated all existing files to PHP, including files located outside of the document root. This behavior creates an information disclosure condition where attackers can differentiate between existing and non-existing files based on the server's response. Although the actual contents of the files are not exposed (PHP treats requests to files outside of the document root as invalid), the ability to enumerate file existence on the system provides valuable reconnaissance information.
It is important to note that production sites using traditional web servers such as Apache, nginx, or Caddy are not affected by this vulnerability. The issue is confined to environments utilizing PHP's built-in server, which is typically employed only during local development.
Root Cause
The root cause of CVE-2025-30207 is a missing path traversal validation in Kirby's router component. The router failed to check whether requested static files were contained within the document root before delegating the request to PHP. This oversight allowed crafted requests containing path traversal sequences (such as ../) to reference files outside the intended web directory, enabling attackers to confirm file existence through response analysis.
Attack Vector
The attack requires adjacent network access, as it primarily affects development environments running PHP's built-in server. An attacker positioned on the same network segment can craft HTTP requests containing path traversal sequences to probe for files outside the document root. By analyzing the differential responses from the server, the attacker can determine whether specific files exist on the target system.
The attack does not require authentication or user interaction. However, the practical impact is limited because the vulnerability only allows file existence enumeration rather than file content disclosure, and it only affects development server configurations.
Detection Methods for CVE-2025-30207
Indicators of Compromise
- HTTP requests containing path traversal sequences such as ../ or ..%2F targeting static file paths
- Unusual patterns of requests probing for common system files outside the web root (e.g., /etc/passwd, configuration files)
- High volumes of requests returning different response codes or timing patterns indicative of file existence probing
Detection Strategies
- Monitor web server access logs for requests containing directory traversal patterns
- Implement web application firewall (WAF) rules to detect and block path traversal attempts
- Review application logs for suspicious request patterns targeting files outside standard web directories
- Deploy network intrusion detection signatures for path traversal attack patterns
Monitoring Recommendations
- Enable detailed logging on development server instances to capture all incoming requests
- Configure alerting for anomalous request patterns that include ../ or encoded variants
- Regularly audit development environments for exposure to untrusted networks
How to Mitigate CVE-2025-30207
Immediate Actions Required
- Upgrade Kirby to version 3.9.8.3, 3.10.1.2, or 4.7.1 or later depending on your version branch
- Avoid exposing PHP's built-in development server to untrusted networks
- Use production-grade web servers (Apache, nginx, or Caddy) for any publicly accessible deployments
- Review network segmentation to ensure development environments are isolated from potentially hostile network segments
Patch Information
The Kirby maintainers have addressed this vulnerability in the following releases:
The fix updates the router to validate that existing static files are contained within the document root. Requests for files outside the document root are now treated as page requests for the error page, eliminating the ability to determine file existence through response analysis.
For detailed information about the vulnerability and the patch, refer to the GitHub Security Advisory GHSA-9p3p-w5jf-8xxg.
Workarounds
- If immediate patching is not possible, avoid using PHP's built-in server and switch to a production web server such as Apache, nginx, or Caddy
- Restrict network access to development server instances by binding only to localhost (127.0.0.1)
- Implement network-level access controls to prevent untrusted hosts from reaching development environments
- Consider using containerized development environments with proper network isolation
The recommended mitigation approach for development environments is to bind PHP's built-in server to the loopback interface only:
# Bind PHP's built-in server to localhost only
php -S 127.0.0.1:8000 kirby/router.php
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
