Detection Guidance

The vulnerability affects the WordPress Töbel Theme versions 1.8.1 and below and allows unauthenticated PHP Object Injection attacks. Detection typically involves identifying the presence of the vulnerable theme version on your system or monitoring for exploitation attempts.

To detect if the vulnerable Töbel theme is installed, you can check the theme version in your WordPress installation by inspecting the theme files or using WP-CLI commands.

• Use WP-CLI to check the installed theme version: wp theme list --status=active
• Manually check the style.css file in the Töbel theme directory (usually wp-content/themes/tobel/) for the version number.

For network detection, monitoring HTTP requests for suspicious payloads that attempt PHP Object Injection or unusual POST requests targeting the theme's PHP files may help identify exploitation attempts.

Patchstack provides a mitigation rule to block attacks until the theme is updated, which can be used in web application firewalls or intrusion detection systems.

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Executive Summary

CVE-2026-39551 is a high-priority PHP Object Injection vulnerability found in the WordPress Töbel Theme versions 1.8.1 and below. It arises from deserialization of untrusted data, allowing attackers to inject malicious objects into the application.

This vulnerability can be exploited without authentication, meaning attackers do not need prior access to the system. If a suitable POP (Property Oriented Programming) chain exists, attackers can leverage this flaw to execute code injection, SQL injection, path traversal, denial of service, and other malicious activities.

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Impact Analysis

This vulnerability can have severe impacts including unauthorized code execution, data breaches through SQL injection, unauthorized file access via path traversal, and service disruption through denial of service attacks.

Because the vulnerability is unauthenticated and highly dangerous, it is expected to be targeted in mass-exploit campaigns affecting thousands of websites regardless of their size or popularity.

Immediate mitigation is necessary to prevent exploitation, either by updating the Töbel theme to version 1.9 or later or by applying a mitigation rule provided by Patchstack.

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Mitigation Strategies

Immediate action is required to mitigate the risk of the PHP Object Injection vulnerability in the Töbel WordPress theme.

• Update the Töbel theme to version 1.9 or later.
• Apply the mitigation rule provided by Patchstack to block attacks until the theme is updated.

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Compliance Impact

The vulnerability in the Töbel WordPress theme allows unauthenticated attackers to perform PHP Object Injection, potentially leading to code execution, SQL injection, path traversal, and denial of service. Such impacts can compromise the confidentiality, integrity, and availability of data.

Because of these risks, organizations using the vulnerable theme may face challenges in maintaining compliance with data protection standards and regulations such as GDPR and HIPAA, which require safeguarding personal and sensitive data against unauthorized access and breaches.

Failure to address this vulnerability could lead to data breaches or service disruptions, which are reportable incidents under these regulations and could result in legal and financial penalties.

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