CVE-2022-3828 in Video Thumbnails Plugin
Summary
by MITRE • 11/28/2022
The Video Thumbnails WordPress plugin through 2.12.3 does not sanitise and escape some of its settings, which could allow high privilege users such as admin to perform Stored Cross-Site Scripting attacks even when the unfiltered_html capability is disallowed (for example in multisite setup).
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Analysis
by VulDB Data Team • 04/25/2025
The Video Thumbnails WordPress plugin version 2.12.3 and earlier contains a critical stored cross-site scripting vulnerability that affects high-privilege users with administrative capabilities. This vulnerability stems from inadequate sanitization and escaping of user-provided input within the plugin's settings framework, creating a persistent security risk that can be exploited even in environments where the unfiltered_html capability has been restricted. The flaw specifically targets the plugin's handling of configuration parameters that are stored in the WordPress database and subsequently rendered without proper output escaping mechanisms.
The technical implementation of this vulnerability occurs when administrators interact with the plugin's settings interface, where user input is processed and stored without sufficient validation and sanitization. When these stored values are later retrieved and displayed within the WordPress admin dashboard or frontend interfaces, the malicious scripts embedded in the configuration parameters execute in the context of other users' browsers. This stored XSS vulnerability operates through the standard XSS attack vector where malicious JavaScript code is injected into persistent storage and then executed when legitimate users access the affected pages.
From an operational perspective, the impact of this vulnerability extends beyond simple data theft or defacement, as it can enable attackers to escalate privileges, steal session cookies, perform unauthorized actions within the WordPress environment, or redirect users to malicious domains. The vulnerability is particularly concerning in multisite WordPress installations where administrators may have elevated privileges but are still subject to the unfiltered_html restrictions, making the attack surface more complex and potentially more damaging. Attackers can leverage this weakness to compromise entire WordPress networks through a single vulnerable plugin installation.
The vulnerability aligns with CWE-79 which describes Cross-Site Scripting flaws, and can be mapped to ATT&CK technique T1548.001 for privilege escalation through the exploitation of administrative capabilities. Security professionals should note that this vulnerability can be exploited even when standard WordPress security measures are in place, as it specifically targets plugin-level configurations rather than core WordPress functionality. Organizations running WordPress multisite environments are particularly at risk since these setups often implement stricter content filtering policies that make the bypass of unfiltered_html capability more significant.
Mitigation strategies should include immediate patching to the latest available version of the Video Thumbnails plugin, which addresses the sanitization issues in the settings handling code. Administrators should also implement additional security monitoring to detect unusual configuration changes and consider implementing Content Security Policy headers to limit the impact of successful XSS attacks. Regular security audits of installed plugins should be conducted to identify similar vulnerabilities in other third-party components, and privileged user accounts should be protected through multi-factor authentication and least privilege access principles to minimize potential damage from successful exploitation attempts.