CVE-2026-81784 in Wise Chat Plugin
Summary
by MITRE • 09/10/2026
Unauthenticated PHP Object Injection in Wise Chat <= 3.4 versions.
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Analysis
by VulDB Data Team • 09/10/2026
The vulnerability identified as an unauthenticated PHP object injection flaw within the Wise Chat plugin for WordPress, specifically affecting versions up to and including 3.4, represents a critical security risk that allows attackers to execute arbitrary code on vulnerable servers without requiring valid credentials. This type of vulnerability stems from the improper handling of user-supplied input during the deserialization process in PHP applications. When an application accepts data from external sources and passes it directly into functions such as unserialize() or similar mechanisms, it creates a pathway for malicious actors to inject crafted serialized objects. In the context of Wise Chat, this flaw likely exists within endpoints that handle chat-related parameters where user input is processed without adequate validation or sanitization before being deserialized by the application logic.
From a technical perspective, PHP object injection exploits the magic methods defined in PHP classes, such as __wakeup(), __destruct(), and __toString(). By injecting a serialized string containing an instance of a class with these dangerous methods, an attacker can trigger side effects that lead to remote code execution (RCE), data exfiltration, or denial of service. The absence of authentication requirements significantly amplifies the severity of this vulnerability because it lowers the barrier for entry, allowing any internet user with network access to exploit the flaw. This aligns closely with CWE-502, which describes Deserialization of Untrusted Data, a category of vulnerabilities where an application deserializes untrusted data without sufficiently verifying that the resulting data will be valid.
The operational impact of this vulnerability is severe and multifaceted. Successful exploitation can result in complete compromise of the underlying web server hosting the WordPress instance. Attackers may gain shell access, allowing them to install backdoors, modify website content, steal sensitive database information including user credentials and personal data, or use the compromised server as a pivot point for further attacks within an internal network. Additionally, since Wise Chat is often used in public-facing environments where users interact freely, the attack surface is broadened by the volume of potential inputs from diverse sources. This scenario maps directly to MITRE ATT&CK technique T1059, specifically Command and Scripting Interpreter sub-techniques like T1059.004 (Unix Shell) or T1059.007 (JavaScript), as well as T1190 for Exploit Public-Facing Application, highlighting the direct path from external access to system compromise.
Mitigation strategies must be implemented immediately by administrators of sites running affected versions of Wise Chat. The primary and most effective remediation is to upgrade the plugin to a version greater than 3.4 where this vulnerability has been patched by the developers. If upgrading is not immediately feasible, temporary mitigations include restricting access to WordPress admin areas via IP whitelisting if applicable, although this does not fully mitigate public-facing chat endpoints. Implementing strict input validation and avoiding deserialization of user-controlled data are critical defensive coding practices that should be reviewed in custom code or plugins. Furthermore, deploying a Web Application Firewall (WAF) with rules specifically tuned to detect serialized payload patterns can provide an additional layer of defense by blocking malicious requests before they reach the application logic. Regular security audits and monitoring for unusual server behavior are also recommended to ensure early detection of any exploitation attempts.