CVE-2026-73389 in Kalles Addons Plugin
Summary
by MITRE • 08/19/2026
Unauthenticated PHP Object Injection in Kalles Addons <= 1.0.6 versions.
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Analysis
by VulDB Data Team • 08/19/2026
The vulnerability identified as an unauthenticated PHP object injection flaw within Kalles Addons versions up to and including 1.0.6 represents a critical security deficiency that allows remote attackers to execute arbitrary code on the target server without requiring valid credentials. This type of vulnerability arises from the application's failure to properly validate or sanitize user-supplied input before it is passed to PHP’s unserialize function, which is commonly used for deserializing data structures such as arrays and objects stored in cookies, POST parameters, or URL arguments. When an attacker provides a crafted serialized string containing maliciously constructed object instances with public properties that trigger dangerous magic methods during the unserialization process, they can manipulate the application's internal state or execute system commands indirectly through available gadget chains.
From a technical perspective, PHP Object Injection exploits the way PHP handles class instantiation and method invocation during deserialization. If an attacker knows or can guess the existence of specific classes within the Kalles Addons plugin or its dependencies that contain public properties and methods like __wakeup(), __destruct(), or __toString(), they can craft a payload that leverages these functions to perform unintended actions. These gadget chains often rely on built-in PHP libraries or third-party packages included in the WordPress environment, such as those used for file handling, database interactions, or HTTP requests. The absence of authentication means this attack vector is particularly dangerous because it lowers the barrier to entry significantly, allowing any internet user with basic scripting knowledge to exploit the flaw remotely via standard web protocols without needing prior access to the administrative dashboard.
The operational impact of successfully exploiting this vulnerability can be severe and far-reaching for organizations relying on WordPress sites running affected versions of Kalles Addons. An attacker who gains control through object injection typically achieves full remote code execution, effectively taking over the compromised server or application instance. This leads to a complete compromise of confidentiality, integrity, and availability. Specific consequences include unauthorized access to sensitive user data such as personal information, financial records, or proprietary business documents stored in the database; defacement of the website’s public-facing content for malicious purposes like phishing or malware distribution; and using the compromised server as a pivot point to launch attacks against other systems within the internal network infrastructure. Additionally, attackers may install persistent backdoors, web shells, or cryptominers that remain undetected by standard security monitoring tools unless specifically configured to detect anomalous PHP execution patterns.
This vulnerability aligns with Common Weakness Enumeration (CWE) category CWE-502, which describes Deserialization of Untrusted Data, and is closely related to CWE-94, Improper Control of Generation of Code ('Code Injection'). In the context of the MITRE ATT&CK framework for enterprise security, this exploitation technique maps primarily to T1059.007, Command and Scripting Interpreter: PHP, as well as T1190, Exploit Public-Facing Application. The unauthenticated nature of the attack also correlates with CWE-287, Improper Authentication, although the root cause is technically a lack of input validation rather than an authentication bypass per se. Understanding these mappings helps security teams prioritize remediation efforts and align their detection rules with established industry standards for identifying similar exploitation patterns in web applications.
To mitigate this vulnerability, immediate action must be taken by updating the Kalles Addons plugin to version 1.0.7 or later where the issue has been resolved through proper input validation and sanitization practices. Developers should ensure that all user-controlled data is never passed directly to unserialize() without rigorous type checking and whitelisting of expected classes. If upgrading is not immediately feasible, temporary mitigations include disabling PHP execution in directories containing uploaded files if applicable, implementing strict Content Security Policies (CSP) to limit script sources, and deploying a Web Application Firewall (WAF) with rules specifically tuned to detect serialized payload patterns associated with known gadget chains. Regular security audits and static code analysis tools should be integrated into the development lifecycle to prevent similar deserialization flaws from being introduced in future releases of WordPress plugins or custom web applications.