CVE-2021-24546 in EditorsKit Plugin
Summary
by MITRE • 10/11/2021
The Gutenberg Block Editor Toolkit – EditorsKit WordPress plugin before 1.31.6 does not sanitise and validate the Conditional Logic of the Custom Visibility settings, allowing users with a role as low contributor to execute Arbitrary PHP code
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Analysis
by VulDB Data Team • 10/14/2021
The vulnerability identified as CVE-2021-24546 affects the Gutenberg Block Editor Toolkit - EditorsKit WordPress plugin, specifically versions prior to 1.31.6. This issue represents a critical security flaw that stems from inadequate input sanitization and validation mechanisms within the plugin's Custom Visibility settings functionality. The vulnerability allows users with minimal privileges, specifically those holding the contributor role, to execute arbitrary PHP code on the affected WordPress installation, creating a severe privilege escalation vector that could compromise entire websites.
The technical flaw resides in the plugin's failure to properly sanitize and validate conditional logic parameters used in the Custom Visibility settings. When users with contributor roles attempt to configure visibility conditions for blocks, the system does not adequately filter or validate the input data, allowing malicious payloads to be injected and subsequently executed as PHP code. This represents a classic code injection vulnerability that operates at the application layer, where user-supplied data is directly incorporated into executable code without proper sanitization. The vulnerability aligns with CWE-94, which describes "Improper Control of Generation of Code ('Code Injection')" and specifically relates to the improper handling of user-controllable input that leads to arbitrary code execution.
The operational impact of this vulnerability is substantial as it enables attackers with minimal privileges to escalate their access and potentially gain full control over WordPress installations. Contributors typically have limited capabilities such as creating and editing their own posts, but this vulnerability allows them to execute arbitrary PHP code, which could lead to complete compromise of the website. Attackers could leverage this to install backdoors, steal sensitive data, deface websites, or use the compromised system as a launch point for further attacks within the network. The vulnerability particularly affects WordPress environments where contributor roles are granted to users who should not have code execution capabilities, creating a significant security risk for organizations that rely on role-based access controls.
Mitigation strategies for this vulnerability should prioritize immediate patching of the affected plugin to version 1.31.6 or later, which includes proper sanitization and validation of conditional logic parameters. Administrators should also implement additional security measures such as restricting file permissions, monitoring for unusual activity patterns, and ensuring that contributor accounts are properly secured with strong authentication mechanisms. The remediation process should include thorough auditing of all plugin installations to identify similar vulnerabilities, as well as implementing web application firewalls and input validation rules to prevent similar issues. Organizations should also consider implementing the principle of least privilege, ensuring that users with contributor roles cannot access functionality that could lead to code execution. This vulnerability demonstrates the importance of proper input validation and sanitization in web applications, aligning with ATT&CK technique T1059.007 for "Command and Scripting Interpreter: PowerShell" and highlighting the necessity of validating all user-supplied inputs to prevent arbitrary code execution attacks.