CVE-2020-35581 in Envira Gallery Lite
Summary
by MITRE • 01/15/2021
A stored cross-site scripting (XSS) issue in Envira Gallery Lite before 1.8.3.3 allows remote attackers to inject arbitrary JavaScript/HTML code via a POST /wp-admin/admin-ajax.php request with the meta[title] parameter.
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Analysis
by VulDB Data Team • 02/14/2021
The CVE-2020-35581 vulnerability represents a critical stored cross-site scripting flaw in the Envira Gallery Lite WordPress plugin version 1.8.3.2 and earlier. This vulnerability exists within the plugin's handling of user input through the WordPress admin-ajax.php endpoint, which serves as a central interface for processing administrative AJAX requests. The flaw allows remote attackers to execute malicious JavaScript code in the context of a victim's browser by manipulating the meta[title] parameter during a POST request to the admin-ajax.php endpoint. This type of vulnerability falls under CWE-79, which specifically addresses cross-site scripting conditions where untrusted data is incorporated into web pages without proper validation or sanitization.
The technical exploitation of this vulnerability occurs when an attacker crafts a malicious POST request to the WordPress admin-ajax.php endpoint, specifically targeting the meta[title] parameter that is used to store gallery item metadata. When the plugin processes this parameter without adequate input sanitization, the malicious JavaScript code becomes permanently stored within the gallery metadata. Subsequently, any user who views the affected gallery page will have the malicious code executed in their browser, creating a persistent XSS attack vector. The stored nature of this vulnerability means that the malicious code remains active until the gallery item is manually modified or deleted, making it particularly dangerous for websites with multiple contributors or administrators.
The operational impact of CVE-2020-35581 extends beyond simple script execution, as it can enable attackers to perform a wide range of malicious activities including session hijacking, credential theft, defacement of website content, and redirection to malicious sites. Attackers can leverage this vulnerability to steal administrator cookies, gain unauthorized access to the WordPress admin panel, or inject additional malicious content that could compromise the entire website. The vulnerability affects any WordPress site using Envira Gallery Lite plugin version 1.8.3.2 or earlier, making it a significant concern for thousands of websites that rely on this popular gallery plugin. The attack vector is particularly concerning because it requires minimal privileges to exploit and can be automated, allowing attackers to target multiple sites simultaneously.
Mitigation strategies for this vulnerability should prioritize immediate plugin updates to version 1.8.3.3 or later, which contain the necessary patches to address the input sanitization issues. Security administrators should also implement comprehensive input validation measures, including sanitizing all user-supplied data before storage and implementing Content Security Policy headers to limit script execution. Additionally, organizations should consider implementing web application firewalls that can detect and block suspicious AJAX requests containing known XSS patterns. The vulnerability aligns with ATT&CK technique T1566.001 for credential access through phishing and T1059.001 for command and scripting interpreter usage, making it a multi-vector threat that requires layered defensive approaches. Regular security audits and vulnerability assessments should be conducted to identify similar issues in other plugins and themes, as this vulnerability demonstrates the importance of proper input validation in WordPress administrative interfaces.