CVE-2023-6933 in Better Search Replace Plugin
Summary
by MITRE • 02/06/2024
The Better Search Replace plugin for WordPress is vulnerable to PHP Object Injection in all versions up to, and including, 1.4.4 via deserialization of untrusted input. This makes it possible for unauthenticated attackers to inject a PHP Object. No POP chain is present in the vulnerable plugin. If a POP chain is present via an additional plugin or theme installed on the target system, it could allow the attacker to delete arbitrary files, retrieve sensitive data, or execute code.
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Analysis
by VulDB Data Team • 04/11/2026
The Better Search Replace plugin for WordPress presents a critical security vulnerability classified as PHP Object Injection in versions up to and including 1.4.4. This vulnerability stems from the plugin's improper handling of untrusted input during the deserialization process, creating a pathway for attackers to inject malicious PHP objects into the application. The flaw exists within the plugin's core functionality where user-supplied data is directly processed through unserialize() functions without adequate sanitization or validation measures. The vulnerability is particularly concerning because it affects all versions up to the specified release, indicating a long-standing issue that has not been properly addressed in the plugin's development lifecycle.
The technical exploitation of this vulnerability occurs when an attacker can manipulate input parameters that are subsequently passed to PHP's unserialize() function. During the deserialization process, PHP reconstructs objects from serialized data, and if this data originates from untrusted sources, it can contain malicious object definitions that execute arbitrary code when instantiated. The vulnerability operates at the core of PHP's object handling mechanisms, where the serialized data can contain method calls or object construction instructions that are executed during the unserialization phase. According to CWE-502, this represents a direct implementation of insecure deserialization practices that have been consistently identified as a high-risk security concern in web applications. The absence of a POP (Points of No Return) chain within the vulnerable plugin itself does not diminish the severity of the issue, as the attack surface can be extended through other components within the WordPress environment.
The operational impact of this vulnerability extends beyond simple exploitation, as it creates a foundation for more sophisticated attacks within the target environment. While the specific plugin does not contain its own chain of method calls that would lead to immediate code execution, attackers can leverage the initial object injection to establish a foothold that allows for further exploitation. The vulnerability enables unauthenticated attackers to potentially delete arbitrary files, retrieve sensitive data, or execute code on the affected system, making it a significant threat to WordPress installations. The attack vector is particularly dangerous because it does not require authentication, meaning any user can potentially exploit the vulnerability, and the impact can range from data exfiltration to complete system compromise. This aligns with ATT&CK technique T1210, which describes exploitation of vulnerabilities in software applications, and the broader category of privilege escalation through application-level attacks.
Mitigation strategies for this vulnerability require immediate action from WordPress administrators to update the Better Search Replace plugin to a version that addresses the deserialization flaw. The recommended approach includes implementing a comprehensive security audit of all installed plugins and themes to identify potential secondary vulnerabilities that could be exploited in conjunction with this issue. Organizations should also consider implementing input validation measures at the web application firewall level to prevent malicious serialized data from reaching the application layer. Additionally, regular security monitoring and vulnerability scanning should be conducted to identify similar issues in other components of the WordPress ecosystem. The vulnerability highlights the importance of proper secure coding practices, particularly in handling user input and object serialization, and underscores the necessity of maintaining up-to-date software components to prevent exploitation of known vulnerabilities.