CVE-2026-16258 in Ajax Search Lite Plugin
Summary
by MITRE • 08/07/2026
The Ajax Search Lite WordPress plugin before 4.14.5 does not prevent the deserialization of untrusted input, allowing unauthenticated attackers to perform PHP Object Injection. When a suitable POP chain is present via another installed Ajax Search Lite WordPress plugin before 4.14.5 or , this can be leveraged to achieve Remote Code Execution.
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Analysis
by VulDB Data Team • 08/07/2026
The Ajax Search Lite WordPress plugin vulnerability represents a critical security flaw that exploits improper input validation and object deserialization practices within the WordPress ecosystem. This vulnerability affects versions prior to 4.14.5 and stems from the plugin's failure to adequately sanitize user-supplied data during the deserialization process, creating an avenue for attackers to inject malicious PHP objects into the application's memory space.
The technical nature of this vulnerability aligns with CWE-502 which specifically addresses "Deserialization of Untrusted Data" as a security weakness that can lead to object injection attacks. When an attacker crafts malicious serialized data and submits it through vulnerable endpoints, the plugin's deserialization mechanism processes this untrusted input without proper validation or sanitization. This flaw enables attackers to manipulate the application's object graph during the reconstruction phase, potentially executing arbitrary code on the server. The vulnerability operates at the core of PHP's serialization mechanism where objects can be reconstructed from serialized strings, making it particularly dangerous when combined with other exploitable components.
The operational impact of this vulnerability extends beyond simple data manipulation or privilege escalation. Unauthenticated attackers can leverage this weakness to achieve remote code execution capabilities without requiring valid credentials or administrative access. This makes the vulnerability particularly attractive to threat actors as it provides a straightforward path to system compromise. The risk is amplified when considering that the vulnerability requires only basic web application interaction skills and can be exploited through standard HTTP requests, making it accessible even to less sophisticated attackers. The potential for widespread exploitation increases with the number of WordPress installations running vulnerable versions of the plugin.
The attack vector specifically targets the PHP object injection mechanism within the Ajax Search Lite plugin's architecture, where attacker-controlled serialized data can be processed through the application's deserialization functions. This creates a potential chain reaction when combined with other installed plugins that may contain suitable POP (Point of Purchase) chains or gadget chains that can be leveraged to execute arbitrary commands on the server. The vulnerability's exploitation pathway typically involves crafting malicious serialized objects that, upon deserialization, trigger code execution through method calls within the application's object model. This type of attack pattern is well-documented in security literature and often classified under ATT&CK technique T1059 which covers Command and Scripting Interpreter.
Organizations should immediately update to version 4.14.5 or later of the Ajax Search Lite plugin to remediate this vulnerability, as the update addresses the core deserialization flaw by implementing proper input validation and sanitization measures. Additionally, implementing web application firewalls with rules specifically designed to detect and block suspicious serialized data patterns can provide additional defense in depth. Security monitoring should include detection of unusual deserialization activities and unauthorized access attempts to plugin endpoints. System administrators should also consider implementing principle of least privilege configurations for WordPress installations and regularly audit installed plugins for known vulnerabilities through automated security scanning tools. The remediation process must include comprehensive testing to ensure that the update does not introduce compatibility issues with existing site functionality while maintaining the security posture against this specific class of attack.