CVE-2023-6692 in Ultimate Blocks Plugin
Summary
by MITRE • 06/19/2024
The Ultimate Blocks – WordPress Blocks Plugin plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the plugin's tab anchor metabox in all versions up to, and including, 3.0.8 due to insufficient input sanitization and output escaping on user supplied attributes. This makes it possible for authenticated attackers with contributor-level and above permissions to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
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Analysis
by VulDB Data Team • 03/23/2025
The vulnerability identified as CVE-2023-6692 affects the Ultimate Blocks WordPress plugin, specifically targeting versions up to and including 3.0.8. This represents a critical security flaw that exploits stored cross-site scripting mechanisms within the plugin's tab anchor metabox functionality. The issue stems from inadequate input sanitization and output escaping measures that fail to properly validate or sanitize user-supplied attributes before they are processed and rendered within the WordPress environment. Attackers with contributor-level permissions or higher can leverage this vulnerability to inject malicious scripts that persist in the system and execute automatically when other users access affected pages.
The technical implementation of this vulnerability occurs within the plugin's metabox handling system where tab anchor elements are processed. When administrators or users with appropriate privileges create or modify content using the plugin's interface, the system fails to adequately sanitize the input parameters that define tab anchor attributes. This insufficient validation creates an opportunity for malicious actors to inject javascript payloads or other malicious code through the user interface elements. The vulnerability is classified as stored XSS because the malicious scripts are permanently stored within the application's database or storage mechanisms rather than being executed through a single request.
From an operational impact perspective, this vulnerability poses significant risks to WordPress installations using the affected plugin. Contributors and higher-level users can potentially compromise the entire site by injecting scripts that execute in the context of other users' browsers. This could lead to session hijacking, data exfiltration, or the execution of unauthorized administrative actions. The attack vector is particularly dangerous because it requires only contributor-level permissions, which are commonly granted to trusted users in many WordPress installations. The vulnerability affects all users who access pages containing the injected content, making it a broad-scope threat that could impact multiple site visitors simultaneously.
Security professionals should note that this vulnerability aligns with CWE-79, which describes Cross-Site Scripting flaws, and maps to ATT&CK technique T1566.001 for the initial access phase through malicious content. The remediation approach must focus on implementing proper input validation and output escaping mechanisms within the plugin's codebase. Immediate mitigation steps include updating to the latest plugin version where the vulnerability has been patched, implementing additional security measures such as content security policies, and conducting thorough audits of user permissions to minimize the attack surface. Organizations should also consider implementing web application firewalls and monitoring for suspicious content injection patterns to detect potential exploitation attempts. The vulnerability demonstrates the critical importance of proper sanitization practices in web applications and highlights the need for comprehensive security testing of all user-facing input mechanisms.