CVE-2023-4402 in Essential Blocks Plugin
Summary
by MITRE • 10/25/2023
The Essential Blocks plugin for WordPress is vulnerable to PHP Object Injection in versions up to, and including, 4.2.0 via deserialization of untrusted input in the get_products function. This allows 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 • 04/10/2026
The Essential Blocks plugin for WordPress represents a widely used collection of customizable blocks that enhance website functionality through various interactive elements. This particular vulnerability affects versions up to and including 4.2.0, making it a significant concern for WordPress administrators who rely on this plugin for their website's dynamic content capabilities. The vulnerability stems from improper input validation within the plugin's codebase, specifically in the get_products function where untrusted data is being deserialized without adequate sanitization measures.
The technical flaw manifests through PHP Object Injection, a class of vulnerability categorized under CWE-502 in the Common Weakness Enumeration system. This occurs when an application deserializes untrusted data without proper validation, allowing attackers to manipulate serialized objects before they are processed. The vulnerability is particularly dangerous because it operates at the PHP serialization level, where attackers can craft malicious serialized objects that, when processed, execute arbitrary code. The get_products function serves as the attack vector where user-provided data is directly fed into the unserialize() function, bypassing all security checks that should normally validate the integrity of serialized data.
The operational impact of this vulnerability is severe for unauthenticated attackers who can exploit it without requiring any credentials or privileged access to the WordPress installation. The vulnerability allows attackers to inject PHP objects that can potentially be used to execute arbitrary commands on the server, delete critical files, or extract sensitive information from the system. While the vulnerable plugin itself does not contain a POP (Points of No Return) chain, the absence of such a chain does not mitigate the overall risk. Attackers can leverage the initial object injection to chain this vulnerability with other plugins or themes installed on the same system that might contain exploitable POP chains, significantly amplifying the potential damage.
Security practitioners should implement immediate mitigations including updating to the patched version of the Essential Blocks plugin, which addresses the deserialization vulnerability by properly validating and sanitizing input data before processing. Additionally, implementing proper input validation at multiple layers of the application architecture can prevent similar vulnerabilities from occurring. The ATT&CK framework categorizes this type of vulnerability under T1210 - Exploitation of Remote Services, specifically targeting the deserialization of untrusted data. Organizations should also consider implementing web application firewalls that can detect and block suspicious serialized data patterns, and conduct regular security audits to identify and remediate similar vulnerabilities across all installed plugins and themes. The vulnerability highlights the importance of secure coding practices and the need for comprehensive security testing of third-party components before deployment.