CVE-2026-27437 in Tennis Club Plugin
Summary
by MITRE • 03/05/2026
Deserialization of Untrusted Data vulnerability in ThemeREX Tennis Club tennis-sportclub allows Object Injection.This issue affects Tennis Club: from n/a through <= 1.2.3.
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Analysis
by VulDB Data Team • 03/06/2026
The vulnerability identified as CVE-2026-27437 represents a critical deserialization flaw within the ThemeREX Tennis Club WordPress theme, specifically impacting versions through 1.2.3. This issue falls under the category of insecure deserialization as defined by CWE-502, where the application processes untrusted data without proper validation or sanitization. The vulnerability manifests as an object injection attack vector that can be exploited by malicious actors to manipulate the deserialization process and potentially execute arbitrary code on the affected system.
The technical flaw occurs when the theme processes user-supplied data that is serialized in a format such as PHP serialized objects or other data structures. When this untrusted data is deserialized without proper input validation, it creates an opportunity for attackers to inject malicious objects that can be executed within the context of the web application. This type of vulnerability is particularly dangerous because it can bypass traditional security measures and directly exploit the application's internal object handling mechanisms. The vulnerability exists in the tennis-sportclub component of the theme, indicating that the specific implementation of data processing within this module fails to properly validate or sanitize incoming serialized data.
The operational impact of this vulnerability extends beyond simple data corruption or unauthorized access. Attackers who successfully exploit this deserialization flaw can potentially achieve remote code execution, allowing them to take full control of the affected WordPress installation. This could result in complete compromise of the website, data theft, defacement, or the installation of backdoors for persistent access. The vulnerability affects not just individual users but can potentially impact entire WordPress networks if the theme is widely deployed. Additionally, the attack surface is expanded because WordPress themes often have access to sensitive system resources and can interact with various plugins and core WordPress functionalities.
Security professionals should consider this vulnerability in the context of the MITRE ATT&CK framework, particularly under the techniques related to command and control, execution, and privilege escalation. The vulnerability aligns with ATT&CK technique T1059.007 for scripting and T1133 for external remote services, as exploitation typically involves sending malicious serialized data to the target system. Organizations should prioritize immediate remediation by updating to the latest version of the Tennis Club theme, which would contain patches addressing the deserialization flaw. System administrators should also implement network monitoring to detect unusual deserialization patterns and consider implementing application firewalls that can detect and block malicious serialized object attempts. Regular security audits of WordPress themes and plugins should include checks for insecure deserialization patterns, and developers should follow secure coding practices that emphasize input validation and proper object handling to prevent similar vulnerabilities from occurring in the future.