CVE-2021-24841 in Helpful Plugin
Summary
by MITRE • 11/17/2021
The Helpful WordPress plugin before 4.4.59 does not sanitise and escape some of its settings, which could allow high privilege users to perform Cross-Site Scripting attacks even when the unfiltered_html capability is disallowed
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Analysis
by VulDB Data Team • 11/19/2021
The CVE-2021-24841 vulnerability affects the Helpful WordPress plugin version 4.4.59 and earlier, representing a critical cross-site scripting flaw that undermines the security posture of WordPress installations. This vulnerability specifically targets the plugin's handling of user settings without proper sanitization and escaping mechanisms, creating an avenue for malicious actors to inject malicious scripts into the application's interface.
The technical flaw stems from the plugin's failure to adequately sanitize user inputs within its administrative settings. When high-privilege users access the plugin's configuration interface, the application processes certain settings without implementing proper output escaping or input validation measures. This omission allows attackers who have gained administrative access or higher privileges to inject malicious JavaScript code that gets executed in the context of other users' browsers. The vulnerability is particularly concerning because it can be exploited even when WordPress's unfiltered_html capability has been properly restricted, which typically prevents XSS attacks by limiting raw HTML input to authorized users.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to perform various malicious activities including credential theft, session hijacking, data exfiltration, and privilege escalation within the WordPress environment. The flaw particularly affects WordPress sites where the Helpful plugin is installed, potentially compromising the entire installation if attackers can leverage the XSS vulnerability to gain further access. The vulnerability's severity is amplified by the fact that it targets high-privilege users, meaning that successful exploitation could provide attackers with administrative control over the affected WordPress site.
Security practitioners should note that this vulnerability aligns with CWE-79 which describes Cross-Site Scripting flaws in web applications, and it maps to ATT&CK technique T1059.007 for Command and Scripting Interpreter: JavaScript. The vulnerability demonstrates a classic failure in input validation and output sanitization that has been consistently identified as a critical weakness in web application security. Organizations should immediately upgrade to version 4.4.59 or later of the Helpful plugin to remediate this vulnerability, while also implementing additional security measures such as regular security audits, input validation checks, and monitoring for suspicious administrative activities. The incident underscores the importance of proper sanitization practices in web applications and highlights how seemingly minor oversights in code can create significant security risks for entire systems.