CVE-2021-24203 in Elementor Website Builder Plugin
Summary
by MITRE • 04/06/2021
In the Elementor Website Builder WordPress plugin before 3.1.4, the divider widget (includes/widgets/divider.php) accepts an ‘html_tag’ parameter. Although the element control lists a fixed set of possible html tags, it is possible for a user with Contributor or above permissions to send a modified ‘save_builder’ request with this parameter set to ‘script’ and combined with a ‘text’ parameter containing JavaScript, which will then be executed when the saved page is viewed or previewed.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 04/10/2021
The CVE-2021-24203 vulnerability affects the Elementor Website Builder WordPress plugin, specifically targeting versions prior to 3.1.4. This security flaw resides within the divider widget implementation located in includes/widgets/divider.php, where the plugin fails to properly validate user input parameters. The vulnerability stems from insufficient sanitization of the 'html_tag' parameter, which should theoretically be restricted to a predefined set of safe HTML elements but can be manipulated by authenticated users with Contributor level permissions or higher. The issue manifests when a malicious user crafts a request to the save_builder endpoint with a modified html_tag parameter set to 'script' combined with JavaScript code in the text parameter.
The technical exploitation of this vulnerability follows a classic cross-site scripting pattern where the plugin's inadequate input validation allows arbitrary HTML tag injection. When a user with sufficient privileges creates or modifies a page containing the divider widget, they can inject a script tag into the html_tag parameter, which then gets rendered as part of the page's HTML output. This occurs because the plugin's validation logic only checks against a limited set of allowed tags but fails to properly sanitize or restrict the input when the parameter is modified through direct API requests. The vulnerability is particularly concerning because it allows execution of arbitrary JavaScript code in the context of the victim's browser, enabling potential data theft, session hijacking, or redirection to malicious sites.
The operational impact of this vulnerability extends beyond simple XSS attacks, as it can be leveraged for more sophisticated attacks within the WordPress environment. An attacker with Contributor privileges can persistently inject malicious code that executes whenever the affected page is viewed or previewed, potentially compromising multiple users who access the compromised content. This vulnerability directly maps to CWE-79 - Cross-site Scripting and aligns with ATT&CK technique T1566.001 - Phishing via Social Media, as the malicious code could be used to harvest credentials or redirect users to malicious domains. The risk is amplified because the attacker doesn't need administrative privileges, making it particularly dangerous in environments where multiple users have contributor-level access.
Mitigation strategies for CVE-2021-24203 should prioritize immediate plugin updates to version 3.1.4 or later, which includes proper input validation and sanitization for the html_tag parameter. Organizations should also implement additional security measures such as restricting contributor-level permissions to only essential tasks, implementing content security policies to prevent script execution, and conducting regular security audits of WordPress plugins. The vulnerability highlights the importance of proper input validation and the principle of least privilege in web application security. Security teams should monitor for exploitation attempts through web application firewalls and implement proper logging of widget modifications to detect unauthorized changes. Additionally, regular security training for content creators and administrators can help prevent accidental or intentional exploitation of such vulnerabilities.