CVE-2026-73397 in Youzify Plugin
Summary
by MITRE • 08/18/2026
Unauthenticated Deserialization of untrusted data in Youzify <= 1.3.7 versions.
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Analysis
by VulDB Data Team • 08/18/2026
The vulnerability identified as an unauthenticated deserialization flaw within Youzify versions prior to or equal to 1.3.7 represents a critical security risk that stems from the improper handling of serialized user input. Deserialization is a common mechanism in many web applications, particularly those built on PHP frameworks like WordPress where plugins such as Youzify operate, allowing complex data structures to be converted into strings for storage or transmission and then reconstructed back into objects when needed. However, this process becomes dangerous when the application accepts untrusted data from external sources without sufficient validation or sanitization before passing it to a deserialization function. In the context of Youzify, which is designed to enhance social networking features on WordPress sites, the plugin processes various user interactions and form submissions that may inadvertently include serialized payloads if an attacker can manipulate these inputs.
The technical core of this vulnerability lies in the application's failure to verify the integrity or origin of the data being deserialized. When a system blindly trusts incoming serialized strings and executes them without checking for malicious content, it creates an opening for Remote Code Execution (RCE). An unauthenticated attacker does not need valid credentials to exploit this flaw because they can craft specific HTTP requests containing maliciously crafted serialized objects. These payloads are designed to trigger side effects during the deserialization process, such as instantiating classes with dangerous methods or invoking functions that interact directly with the underlying server environment. This bypasses standard authentication mechanisms entirely, making it one of the most severe types of vulnerabilities in web application security landscapes.
From an operational perspective, the impact of this vulnerability is profound and potentially catastrophic for any organization running a vulnerable version of Youzify. Successful exploitation allows attackers to execute arbitrary code on the server hosting the WordPress site with the privileges of the web service process. This can lead to complete compromise of the website's backend, including access to sensitive databases containing user personal information, financial records, or proprietary business data. Attackers may use this foothold to install backdoors, deface websites, launch further attacks against internal networks if the server is part of a larger infrastructure, or engage in cryptomining activities using the compromised resources. The lack of authentication requirement means that automated scanning tools can easily discover and exploit these instances at scale across the internet, leading to widespread compromise incidents.
This vulnerability aligns with CWE-502, which describes Deserialization of Untrusted Data, a category recognized by industry standards as highly dangerous due its potential for remote code execution. Furthermore, in terms of offensive security frameworks like MITRE ATT&CK, this exploit technique maps closely to T1059 Command and Scripting Interpreter or potentially T1190 Exploit Public-Facing Application depending on the specific vector used to deliver the payload. The absence of input validation is a classic example of CWE-20 Improper Input Validation, which serves as the root cause allowing the malicious serialized data to pass through security controls unnoticed until it reaches the deserialization endpoint.
To mitigate this risk, administrators must immediately upgrade Youzify to version 1.3.8 or later where these issues have been addressed by implementing strict input validation and ensuring that only trusted sources are allowed for deserialization operations. If upgrading is not immediately feasible, temporary mitigations include restricting access to the affected endpoints via Web Application Firewall rules that detect known malicious serialized patterns or disabling specific plugin features that handle untrusted user inputs until a patch can be applied. Regular security audits and code reviews focusing on data handling practices are essential to prevent similar vulnerabilities in future development cycles. Organizations should also implement principle of least privilege for their web server processes to limit the potential damage if an exploitation attempt succeeds, ensuring that even if deserialization occurs, the attacker cannot easily escalate privileges or access critical system files outside the designated application directory.