CVE-2022-4473 in Widget Shortcode Plugin
Summary
by MITRE • 02/13/2023
The Widget Shortcode WordPress plugin through 0.3.5 does not validate and escape some of its shortcode attributes before outputting them back in the page, which could allow users with a role as low as contributor to perform Stored Cross-Site Scripting attacks which could be used against high privilege users such as admins.
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Analysis
by VulDB Data Team • 03/12/2023
The CVE-2022-4473 vulnerability affects the Widget Shortcode WordPress plugin version 0.3.5 and earlier, representing a critical stored cross-site scripting flaw that undermines the security posture of WordPress installations. This vulnerability stems from inadequate input validation and output escaping mechanisms within the plugin's shortcode processing functionality, creating an avenue for malicious actors to inject persistent malicious scripts into web pages. The flaw is particularly concerning because it requires only contributor-level user privileges to exploit, making it accessible to users who typically have limited capabilities within WordPress systems. The vulnerability allows attackers to craft malicious shortcode attributes that, when processed by the plugin, get stored in the database and subsequently executed whenever the page containing the shortcode is rendered to other users, including administrators and high-privilege accounts.
The technical implementation of this vulnerability resides in the plugin's failure to properly sanitize and escape shortcode attributes before incorporating them into the HTML output generated by the WordPress rendering engine. When a contributor user creates or modifies content containing a malicious shortcode with specially crafted attributes, the plugin processes these attributes without adequate validation, allowing potentially dangerous HTML or JavaScript code to be embedded directly into the page markup. This stored XSS vulnerability operates through the standard WordPress shortcode mechanism where attributes passed to shortcodes are processed and rendered back to users, creating a persistent threat vector that can affect any user who views the compromised page. The vulnerability is classified under CWE-79 as a failure to escape output, specifically manifesting as a stored cross-site scripting attack that can be leveraged against users with higher privileges.
The operational impact of this vulnerability extends beyond simple data theft or defacement, as it provides attackers with the ability to escalate privileges and execute arbitrary code within the context of high-privilege user sessions. When administrators or other elevated users view pages containing the malicious shortcode, their browsers execute the stored JavaScript payloads, potentially allowing attackers to steal session cookies, perform actions on behalf of the victim, or redirect users to malicious sites. This vulnerability directly maps to ATT&CK technique T1566.001 for credential access through social engineering, and T1059.001 for execution through scripting, as it enables attackers to establish persistent access through client-side exploitation. The threat is particularly severe because contributors typically have access to content creation features, making it relatively easy for attackers to find and exploit this vulnerability in compromised WordPress installations.
Mitigation strategies for CVE-2022-4473 should prioritize immediate plugin updates to version 0.3.6 or later, which contain the necessary patches to address the input validation and output escaping deficiencies. Organizations should implement comprehensive security monitoring to detect and remove any existing malicious shortcodes that may have been injected into their systems before the patch was applied. Additionally, implementing proper input validation at multiple layers including content creation interfaces, database storage, and output rendering can provide defense-in-depth against similar vulnerabilities. Security teams should consider restricting contributor-level permissions to prevent unauthorized shortcode creation where possible, and implement web application firewalls that can detect and block suspicious shortcode attributes. The vulnerability underscores the importance of proper secure coding practices including input validation, output escaping, and principle of least privilege in plugin development, particularly for WordPress plugins that handle user-generated content processing.