CVE-2025-4682 in Essential Blocks Plugin
Summary
by MITRE • 05/27/2025
The Essential Blocks – Page Builder Gutenberg Blocks, Patterns & Templates plugin for WordPress is vulnerable to Stored Cross-Site Scripting via HTML attributes in Slider and Post Carousel widgets in all versions up to, and including, 5.4.0 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with Contributor-level access and above, 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 • 05/27/2025
The Essential Blocks plugin for WordPress represents a popular suite of Gutenberg blocks designed to enhance page building capabilities through various widgets including sliders and post carousels. This vulnerability affects all versions up to and including 5.4.0, creating a significant security risk within WordPress environments that utilize this plugin. The flaw exists in the plugin's handling of HTML attributes within specific widget components, particularly the Slider and Post Carousel widgets that are commonly used for content presentation and navigation purposes.
The technical root cause of this vulnerability stems from inadequate input sanitization and insufficient output escaping mechanisms within the plugin's codebase. When authenticated users with Contributor-level access or higher create or modify content using these widgets, the plugin fails to properly validate and sanitize HTML attributes that are passed through user input. This insufficient sanitization allows malicious scripts to be stored within the WordPress database, where they remain dormant until accessed by other users. The vulnerability specifically affects the Slider and Post Carousel widgets, which are frequently used in blog posts, landing pages, and other content areas where user-generated content might be displayed.
The operational impact of this stored cross-site scripting vulnerability is substantial as it enables authenticated attackers to inject arbitrary web scripts that will execute whenever any user accesses a page containing the malicious content. This creates a persistent threat vector that can be exploited to steal user sessions, redirect visitors to malicious sites, or perform actions on behalf of users. The vulnerability's scope extends beyond simple script injection, as it can potentially be leveraged to escalate privileges or gain unauthorized access to sensitive system resources. Since the attack requires only Contributor-level access, it represents a particularly concerning risk for WordPress installations where multiple users have varying permission levels.
This vulnerability aligns with CWE-79, which describes Cross-Site Scripting flaws resulting from insufficient input sanitization and output escaping. The ATT&CK framework categorizes this as a technique for Code Injection, specifically targeting web applications through stored XSS vulnerabilities. Organizations using this plugin face a critical security exposure that could be exploited by attackers who gain access to accounts with Contributor permissions or higher, potentially compromising entire WordPress installations. The stored nature of the vulnerability means that even if the initial attack occurs during content creation, the malicious scripts will continue to execute whenever any user accesses affected pages, creating a persistent threat that can affect multiple users over extended periods.
The recommended mitigation strategy involves immediate patching of the Essential Blocks plugin to version 5.4.1 or later, which contains the necessary security fixes to address the input sanitization and output escaping deficiencies. System administrators should also implement additional monitoring measures to detect unusual content modifications and conduct regular security audits of user permissions to minimize the attack surface. Organizations should consider implementing web application firewalls and content security policies to provide additional layers of protection against similar vulnerabilities. Regular security updates and patch management procedures should be enforced across all WordPress plugins and themes to prevent similar issues from arising in the future.