DefaultFuction CMS 1.0 Command Injection Vulnerability (CVE-2026-5333)

On April 2, 2026, a command injection vulnerability, CVE-2026-5333, was disclosed in DefaultFuction Content-Management-System version 1.0. The vulnerability resides in the /admin/tools.php file and is triggered by manipulating the host argument. This allows remote attackers to inject and execute arbitrary commands on the system. The existence of a public exploit increases the risk of exploitation, making it crucial for organizations using this CMS version to implement mitigation measures. The affected software has a limited user base, but successful exploitation can lead to complete system compromise.

Attack Chain

1. The attacker identifies a vulnerable DefaultFuction CMS 1.0 instance.
2. The attacker sends a crafted HTTP request to /admin/tools.php, manipulating the host parameter with an injected command.
3. The application fails to properly sanitize or validate the host parameter.
4. The injected command is executed by the underlying operating system with the privileges of the web server.
5. The attacker gains initial access to the server.
6. The attacker may attempt to escalate privileges using publicly available exploits or misconfigurations.
7. The attacker installs a web shell or other persistent access mechanism.
8. The attacker performs reconnaissance on the internal network and exfiltrates sensitive data or causes other damage.

Impact

Successful exploitation of CVE-2026-5333 allows a remote attacker to execute arbitrary commands on the affected server. This can lead to complete compromise of the system, including sensitive data theft, modification of website content, and potential lateral movement within the network. Given the publicly available exploit, the risk of widespread exploitation is significant for unpatched DefaultFuction CMS 1.0 instances.

Recommendation

• Apply any available patches or updates for DefaultFuction Content-Management-System 1.0 to address CVE-2026-5333.
• Deploy the Sigma rule Detect Suspicious HTTP Request to admin/tools.php to detect exploitation attempts in web server logs.
• Monitor web server logs for suspicious activity, especially requests containing shell commands in the host parameter.
• Implement input validation and sanitization measures to prevent command injection vulnerabilities in web applications.
• Restrict access to the /admin/tools.php file to authorized users only.