CVE-2023-5809 in Popup Box Plugin
Summary
by MITRE • 12/05/2023
The Popup box WordPress plugin before 3.8.6 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 • 12/23/2023
The vulnerability identified as CVE-2023-5809 affects the Popup box WordPress plugin version 3.8.5 and earlier, presenting a critical security risk through stored cross-site scripting vulnerabilities. This flaw specifically targets the plugin's handling of user settings without proper sanitization and escaping mechanisms, creating an avenue for malicious actors to inject persistent malicious scripts into the WordPress environment.
The technical implementation of this vulnerability stems from the plugin's failure to adequately sanitize user input within its administrative settings. When high-privilege users such as administrators interact with the plugin's configuration interface, the system does not properly validate or escape potentially malicious content entered into various fields. This oversight allows attackers to store malicious scripts that will execute whenever the affected pages are loaded, regardless of the standard security restrictions that typically protect against such attacks.
The operational impact of this vulnerability becomes particularly severe in multisite WordPress configurations where the unfiltered_html capability is explicitly restricted to prevent unauthorized script execution. Even under these security-restricted conditions, the vulnerability allows administrators to bypass these protections through the plugin's settings interface, effectively undermining the security model designed to prevent stored XSS attacks. This creates a persistent threat vector where malicious scripts can remain active and execute against all users who access the affected WordPress sites.
The vulnerability aligns with CWE-79, which specifically addresses cross-site scripting flaws in software applications. This classification indicates that the plugin fails to properly handle user-supplied data, allowing malicious content to be executed in the context of other users' browsers. The ATT&CK framework categorizes this as a technique for code injection, specifically targeting the web application layer where user input is not properly validated or escaped.
Organizations should immediately update to version 3.8.6 or later of the Popup box plugin to remediate this vulnerability. Additionally, administrators should conduct thorough audits of all installed plugins to identify similar sanitization issues, particularly in plugins that handle user-facing configuration settings. Security monitoring should be enhanced to detect unusual administrative activities that might indicate exploitation attempts, and regular security assessments should be performed to identify potential input validation gaps in custom and third-party WordPress plugins. The vulnerability demonstrates the critical importance of proper input sanitization and output escaping in web applications, particularly those handling user-generated content in administrative contexts where elevated privileges can be leveraged to create persistent security threats.