Deserialization of Untrusted Data in RT-Theme 18 Extensions

Executive Summary

CVE-2026-57744 is a vulnerability in the WordPress RT-Theme 18 | Extensions Plugin versions 2.5 and below that allows PHP Object Injection through deserialization of untrusted data.

This flaw enables attackers to inject malicious objects into the application, potentially leading to code execution, SQL injection, path traversal, denial of service, or other harmful actions if a suitable Property-Oriented Programming (POP) chain exists.

The vulnerability is unauthenticated, meaning attackers do not need valid user credentials to exploit it, making it highly dangerous and likely to be targeted in widespread attacks.

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Detection Guidance

Detecting the CVE-2026-57744 vulnerability on your network or system involves checking for the presence of the affected WordPress RT-Theme 18 | Extensions plugin and monitoring for signs of exploitation. Below are some suggested methods and commands to help identify the vulnerability or potential attacks.

• Check the installed version of the RT-Theme 18 | Extensions plugin on your WordPress site. The vulnerability affects versions 2.5 and below. You can verify the plugin version by navigating to the WordPress admin dashboard, then going to 'Plugins' and locating the RT-Theme 18 | Extensions plugin. The version number will be displayed there.
• Use the WordPress command-line interface (WP-CLI) to check the plugin version. Run the following command: wp plugin list --name=rt18-extensions --fields=name,version,status. This will display the installed version of the plugin.
• Monitor web server logs for unusual or suspicious activity, particularly requests that may indicate exploitation attempts. Look for patterns such as unexpected serialized data in HTTP requests, especially in POST parameters or cookies. For example, you can use grep to search for serialized PHP objects in Apache or Nginx logs: grep -r 'O:[0-9]:' /var/log/apache2/ or grep -r 'O:[0-9]:' /var/log/nginx/.
• Deploy a web application firewall (WAF) or intrusion detection system (IDS) to detect and block exploitation attempts. Patchstack has issued a temporary mitigation rule that can be integrated into security tools like ModSecurity or other WAF solutions to block attacks targeting this vulnerability.
• Use vulnerability scanning tools that support WordPress plugin checks, such as WPScan or Nessus, to identify if the affected plugin is installed and vulnerable. For example, you can run WPScan with the following command: wpscan --url your-wordpress-site.com --enumerate vp. This will scan for vulnerable plugins.
• Review your WordPress site for any unexpected or unauthorized changes, such as new admin users, modified files, or suspicious code injections. This can indicate that the vulnerability has already been exploited.

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Impact Analysis

Exploitation of this vulnerability can lead to severe impacts including remote code execution, unauthorized database access via SQL injection, file system access through path traversal, denial of service, and other malicious activities.

Because the vulnerability requires no authentication, attackers can easily exploit it to compromise affected WordPress websites, potentially leading to data breaches, website defacement, service outages, or full system compromise.

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Compliance Impact

The CVE-2026-57744 vulnerability, which involves deserialization of untrusted data leading to PHP object injection, can significantly impact compliance with standards and regulations like GDPR and HIPAA.

• GDPR: The vulnerability allows unauthenticated attackers to execute malicious activities such as code injection, SQL injection, or denial of service. If exploited, this could lead to unauthorized access to or exfiltration of personal data, violating GDPR's requirements for data protection and confidentiality (Articles 5, 25, and 32). A successful attack could result in a data breach, triggering mandatory reporting obligations under Article 33 and potential fines under Article 83.
• HIPAA: For organizations handling protected health information (PHI), this vulnerability poses a risk of unauthorized access to sensitive patient data. Exploitation could lead to a breach of PHI, violating the HIPAA Security Rule (45 CFR Part 164, Subpart C), which requires safeguards to ensure the confidentiality, integrity, and availability of electronic PHI. Non-compliance could result in penalties under the HIPAA Enforcement Rule.
• General Compliance Risks: The vulnerability is classified under OWASP Top 10 A3: Injection, which is a well-known security risk. Failure to address such critical vulnerabilities may indicate inadequate security controls, violating requirements in frameworks like ISO 27001, NIST SP 800-53, or PCI DSS, depending on the organization's regulatory obligations.

Organizations using the affected plugin must mitigate this vulnerability promptly to avoid compliance violations and potential legal or financial consequences.

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Mitigation Strategies

The vulnerability affects WordPress RT-Theme 18 | Extensions Plugin versions 2.5 and below and allows unauthenticated PHP Object Injection attacks.

As there is no official patch available yet, immediate mitigation steps include:

• Update the plugin immediately to a version above 2.5 if available.
• If updating is not possible, apply temporary mitigation rules provided by Patchstack to block attacks.
• Seek assistance from your hosting provider or web developer to implement these mitigations.
• Consider using automated vulnerability mitigation solutions offered by Patchstack to protect your website until an official fix is released.

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