From this webpage screenshot, the following key vulnerability information can be obtained: 1. **Vulnerability Overview**: - **Vulnerability Title**: Phar Deserialization leading to Arbitrary File Deletion in my little forum <= 20251129.1 - **Vulnerability Description**: This vulnerability allows attackers to delete arbitrary files by uploading a specially crafted image file and exploiting a Phar deserialization issue. - **CVE ID**: CVE-2026-25923 2. **Affected Versions and Environment**: - **Affected Version**: mylittleforum <= 20251129.1 - **Affected PHP Versions**: PHP < 8.0 (7.3, 7.4) - **Affected Files**: - includes/functions.inc.php - includes/functions.inc.php - includes/upload_image.inc.php 3. **Vulnerability Details and Root Cause**: - **Vulnerability Types**: CWE-434 Unrestricted Upload of File with Dangerous Type, CWE-502 Deserialization of Untrusted Data - **Root Cause**: The application fails to filter the `phar://` protocol during URL validation, allowing attackers to upload malicious Phar Polyglot files and trigger Phar deserialization via the BBCode image tag `[img]`. - **Vulnerable Code**: - Code lacking `phar://` filtering is located in includes/functions.inc.php. - Code triggering `phar://` is located in includes/functions.inc.php. 4. **Impact and Exploitation**: - **Impact**: May lead to Denial of Service (DoS), deletion of critical configuration files, .htaccess files, uploaded images, theme files, or other application data; permanent damage (deletion of installation files preventing system recovery). - **Exploitation Prerequisites**: - PHP version < 8.0 - Image upload feature enabled (disabled by default, but typically enabled for forums) - BBCode enabled - User has posting permissions - **Attack Vector**: - Upload malicious Phar Polyglot file - Inject BBCode tag - Trigger Phar deserialization - Execute Smarty 4.1.0 POP chain 5. **Mitigation and Remediation Recommendations**: - **Immediate Fixes**: - Add `phar://` protocol to blacklist - Validate image content - Disable Phar stream wrapper - Upgrade to PHP 8.0+ - **Long-term Recommendations**: - Conduct security audits - Implement input validation - Update dependencies