CVE-2021-24543 in jQuery Reply to Comment Plugin
Summary
by MITRE • 10/25/2021
The jQuery Reply to Comment WordPress plugin through 1.31 does not have any CSRF check when saving its settings, nor sanitise or escape its 'Quote String' and 'Reply String' settings before outputting them in Comments, leading to a Stored Cross-Site Scripting issue.
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Analysis
by VulDB Data Team • 10/30/2021
The CVE-2021-24543 vulnerability affects the jQuery Reply to Comment WordPress plugin version 1.31 and earlier, presenting a critical security flaw that combines insufficient cross-site request forgery protection with improper input sanitization. This vulnerability specifically targets the plugin's settings handling mechanism where administrative configurations are saved without proper CSRF validation, creating an avenue for unauthorized modifications. The flaw is particularly dangerous because it operates within the WordPress ecosystem where administrators often have elevated privileges and access to sensitive system functions.
The technical implementation of this vulnerability stems from the plugin's failure to implement proper CSRF tokens when processing configuration changes through the WordPress admin interface. When administrators modify the plugin settings, particularly the 'Quote String' and 'Reply String' parameters, these values are stored without adequate sanitization or escaping mechanisms. The plugin's code does not properly validate or sanitize user input before storing it in the database, nor does it escape output when displaying these values in comment contexts. This dual failure creates a perfect storm for stored cross-site scripting attacks where malicious actors can inject malicious scripts that will execute whenever comments are rendered.
The operational impact of this vulnerability extends beyond simple script execution as it enables attackers to perform various malicious activities including session hijacking, credential theft, and unauthorized administrative actions. When the 'Quote String' and 'Reply String' settings are displayed in comment contexts, the lack of proper output escaping allows attackers to inject JavaScript code that can capture user credentials, redirect browsers to malicious sites, or even escalate privileges within the WordPress environment. The stored nature of this vulnerability means that once injected, malicious scripts persist and execute every time affected comments are loaded, making it particularly dangerous for high-traffic websites where comment systems are frequently accessed.
The vulnerability aligns with CWE-352, which specifically addresses Cross-Site Request Forgery, and CWE-79, which covers Cross-Site Scripting, demonstrating how multiple security weaknesses compound to create more severe threats. From an ATT&CK framework perspective, this vulnerability maps to T1059.007 for Command and Scripting Interpreter, T1566 for Phishing, and T1078 for Valid Accounts, as attackers can leverage this flaw to establish persistent access through compromised administrative sessions. The vulnerability's exploitation requires minimal privileges and can be automated, making it particularly attractive to threat actors. Organizations should immediately update to patched versions of the plugin, implement proper input validation and output escaping mechanisms, and consider additional security measures such as content security policies to mitigate the risk of successful exploitation.