CVE-2026-116390 in Filter Everything Plugin
Summary
by MITRE • 10/28/2026
Deserialization of Untrusted Data vulnerability in stepasyuk Filter Everything — WordPress & WooCommerce Filters filter-everything allows Object Injection.This issue affects Filter Everything — WordPress & WooCommerce Filters: from n/a through 1.9.7.
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Analysis
by VulDB Data Team • 10/28/2026
The vulnerability identified as a deserialization of untrusted data flaw within the stepasyuk Filter Everything plugin for WordPress and WooCommerce represents a critical security risk that stems directly from improper handling of user-supplied input during object reconstruction processes. This specific issue, classified under CWE-502 Deserialization of Untrusted Data, occurs because the application accepts serialized PHP objects from external sources without sufficient validation or sanitization before passing them to internal deserialization functions such as unserialize(). In modern web development, particularly within content management systems like WordPress, plugins often rely on serialization for caching mechanisms, state persistence, and configuration storage. When a plugin fails to verify the integrity of these data structures against an allowlist of expected classes or methods, it creates a pathway for attackers to inject malicious payloads that exploit built-in PHP magic methods during the unserialization process.
The technical flaw lies in the lack of strict type checking and class whitelisting when processing filter configurations submitted by users. In versions ranging from n/a through 1.9.7, the plugin likely accepts serialized data strings via GET or POST parameters without adequately restricting which classes can be instantiated during deserialization. This oversight allows an attacker to craft a specially formatted PHP object that, once unserialized, triggers specific magic methods such as __wakeup(), __destruct(), or __toString(). These methods are executed automatically by the PHP engine and often contain logic for resource cleanup, database queries, or file operations. By manipulating these entry points, an adversary can achieve arbitrary code execution on the server hosting the vulnerable application, effectively bypassing standard authentication mechanisms if the affected function is accessible to lower-privileged user roles such as subscribers or contributors who typically have limited access rights in a WordPress environment.
From an operational perspective, this vulnerability enables severe consequences including remote code execution (RCE), which can lead to complete compromise of the underlying server infrastructure. Attackers may leverage this flaw to install web shells, exfiltrate sensitive database contents containing user credentials and personal information, or pivot further into internal networks if the WordPress instance is part of a larger ecosystem. The impact extends beyond immediate data loss; it undermines the integrity and availability of the service, potentially leading to defacement, denial of service through resource exhaustion via crafted objects, and significant reputational damage for site owners who rely on this plugin for filtering content or products in their WooCommerce stores. Furthermore, because WordPress plugins are widely distributed and often installed by non-technical administrators, the prevalence of vulnerable instances increases the attack surface significantly across the web ecosystem.
To mitigate this risk, immediate action is required to update the Filter Everything plugin to a version newer than 1.9.7 where the developer has presumably implemented proper input validation or removed unsafe deserialization practices. In cases where updating is not immediately feasible, administrators should disable the affected functionality if possible and restrict user roles that can submit filter configurations to only those with administrative privileges. Implementing server-side controls such as disabling dangerous PHP functions like unserialize() for untrusted inputs via php.ini settings provides an additional layer of defense. Long-term remediation strategies must include adopting secure coding standards that prioritize serialization safety, such as using JSON instead of native PHP serialization where possible, or strictly enforcing class whitelists during deserialization to ensure only expected and safe classes are instantiated from incoming data streams.
This vulnerability aligns with the MITRE ATT&CK framework technique T1059 Command and Scripting Interpreter, specifically under sub-techniques involving system commands or scripting engines like PHP. It also relates to CWE-20 Improper Input Validation and CWE-78 OS Command Injection if the deserialized object leads to command execution. Security teams should prioritize patching this vulnerability due to its high severity rating associated with remote code execution capabilities in widely used e-commerce and content management platforms, ensuring that all instances of the plugin are upgraded promptly to eliminate the attack vector entirely.