CVE-2022-50806: 4images 1.9 RCE Vulnerability

CVE-2022-50806 Overview

CVE-2022-50806 is a remote command execution vulnerability affecting 4images version 1.9, a popular web-based image gallery management system. This vulnerability allows authenticated administrators to inject and execute arbitrary commands through the application's template editing functionality. Attackers with administrative access can save malicious reverse shell code in templates and trigger execution by accessing the categories.php endpoint with a specially crafted cat_id parameter.

Critical Impact

Authenticated administrators can achieve full remote command execution on the underlying server, potentially leading to complete system compromise, data exfiltration, and lateral movement within the network.

Affected Products

• 4images version 1.9

Discovery Timeline

• 2026-01-13 - CVE CVE-2022-50806 published to NVD
• 2026-01-13 - Last updated in NVD database

Technical Details for CVE-2022-50806

Vulnerability Analysis

This vulnerability falls under CWE-94 (Improper Control of Generation of Code, also known as Code Injection). The 4images application fails to properly sanitize or restrict the content that can be saved within template files. When an authenticated administrator modifies template content through the administrative interface, malicious PHP code or shell commands can be embedded directly into the template.

The vulnerability is particularly concerning because template files are processed by the PHP interpreter when accessed. This means any injected code will be executed with the privileges of the web server process. While the vulnerability requires administrative authentication, compromised admin credentials or insider threats could leverage this flaw for complete server takeover.

Root Cause

The root cause lies in the template editing functionality's failure to validate and sanitize user-supplied content before saving it to template files. The application trusts that administrative users will only input legitimate template code, without implementing any code execution restrictions or content filtering. This design flaw allows arbitrary code, including reverse shell payloads, to be persisted in template files.

Attack Vector

The attack is carried out over the network and requires the following sequence:

1. An attacker gains access to an administrator account (through credential theft, brute force, or social engineering)
2. Using the administrative template editing interface, the attacker injects malicious reverse shell code into a template file
3. The attacker then navigates to the categories.php endpoint with a crafted cat_id parameter
4. The malicious template is processed, executing the injected payload on the server
5. A reverse shell connection is established, giving the attacker interactive command-line access to the server

The exploitation path demonstrates a stored code injection attack pattern where the payload persists in template storage and executes upon specific page requests.

Detection Methods for CVE-2022-50806

Indicators of Compromise

• Unexpected modifications to template files in the 4images installation directory
• Suspicious PHP code patterns in template files, especially containing functions like exec(), system(), shell_exec(), passthru(), or socket-related code
• Unusual outbound network connections from the web server process
• Anomalous access patterns to categories.php with unusual cat_id parameter values

Detection Strategies

• Implement file integrity monitoring (FIM) on template directories to detect unauthorized modifications
• Review web server access logs for suspicious requests to categories.php with atypical parameter values
• Monitor for unusual process spawning from the web server (e.g., Apache, Nginx, PHP-FPM)
• Deploy web application firewall (WAF) rules to detect code injection patterns in administrative requests

Monitoring Recommendations

• Enable detailed logging for all administrative actions within 4images
• Configure network monitoring to alert on reverse shell connection patterns (outbound connections to unusual ports)
• Implement behavioral analysis to detect anomalous administrator activity patterns
• Set up alerts for any changes to template files outside of scheduled maintenance windows

How to Mitigate CVE-2022-50806

Immediate Actions Required

• Review all administrator accounts and enforce strong authentication including multi-factor authentication (MFA)
• Audit existing template files for any suspicious or unauthorized code
• Restrict administrative access to trusted IP addresses only
• Consider temporarily disabling template editing functionality until a patch is available

Patch Information

No official vendor patch has been identified in the available data. Organizations using 4images 1.9 should monitor the 4homepages official website for security updates. Additional technical details about this vulnerability can be found in the VulnCheck Security Advisory and Exploit-DB #51147.

Workarounds

• Implement network-level access controls to restrict administrative interface access to trusted networks only
• Deploy a web application firewall with rules to block code injection patterns in request bodies
• Run the web server with minimal privileges and in a containerized or sandboxed environment
• Consider migrating to an actively maintained image gallery solution if no patch becomes available
• Implement file system permissions that prevent the web server from modifying template files directly

# Configuration example - Restrict template directory permissions
# Remove write permissions for web server user on template files
chmod 444 /path/to/4images/templates/*.html
chown root:root /path/to/4images/templates/*.html

# Configure firewall to restrict admin panel access (iptables example)
iptables -A INPUT -p tcp --dport 443 -s TRUSTED_IP_RANGE -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -m string --string "/admin/" --algo bm -j DROP