CVE-2022-1063 in Thank Me Later Plugin
Summary
by MITRE • 04/18/2022
The Thank Me Later WordPress plugin through 3.3.4 does not sanitise and escape the Message Subject field before outputting it in the Messages list, which could allow high privileges users such as admin to perform Cross-Site Scripting attacks even when the unfiltered_html capability is disallowed
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Analysis
by VulDB Data Team • 04/21/2022
The CVE-2022-1063 vulnerability resides within the Thank Me Later WordPress plugin version 3.3.4 and earlier, representing a critical cross-site scripting flaw that exploits improper input sanitization in the plugin's message handling functionality. This vulnerability specifically targets the Message Subject field within the plugin's Messages list interface, where user-provided input fails to undergo proper sanitization and escaping before being rendered in the web interface. The flaw occurs because the plugin does not adequately validate or sanitize the subject field content before outputting it to the browser, creating a persistent XSS vector that can be exploited by malicious actors with administrative privileges.
The technical nature of this vulnerability aligns with CWE-79, which categorizes cross-site scripting as a code injection flaw where untrusted data is executed as code in the victim's browser. The vulnerability is particularly concerning because it operates within a context where the unfiltered_html capability is typically restricted, yet still allows for XSS execution through the Message Subject field. This suggests that the plugin's sanitization logic is bypassed or insufficiently implemented, potentially allowing attackers to inject malicious scripts that execute in the context of other users' browsers. The vulnerability affects high privilege users such as administrators, which amplifies the potential impact as these users typically have access to sensitive data and system functionalities.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to perform session hijacking, steal sensitive information, manipulate data, or redirect users to malicious websites. Given that the plugin is designed for WordPress environments where administrators often handle sensitive communications, successful exploitation could lead to complete compromise of the affected WordPress site. The vulnerability's persistence in the Messages list interface means that any malicious script injected into the subject field would execute every time the list is displayed, potentially affecting multiple users who view the messages. This makes the attack surface particularly broad and the impact cumulative over time.
Mitigation strategies for CVE-2022-1063 should prioritize immediate plugin updates to versions that address the sanitization flaw, as this represents the most direct solution to the vulnerability. Organizations should also implement additional security measures such as input validation at multiple layers, content security policies to prevent script execution, and regular security audits of WordPress plugins. The ATT&CK framework's T1059.008 technique for "Scripting" is relevant here, as this vulnerability enables attackers to execute malicious scripts through the XSS vector. Additionally, implementing web application firewalls and monitoring for suspicious input patterns can help detect and prevent exploitation attempts. Regular patch management processes should be strengthened to ensure timely updates of all WordPress plugins and themes, as this vulnerability demonstrates how outdated plugins can provide persistent attack vectors even in environments with otherwise secure configurations.