CVE-2021-24873 in Tutor LMS Plugin
Summary
by MITRE • 11/23/2021
The Tutor LMS WordPress plugin before 1.9.11 does not sanitise and escape user input before outputting back in attributes in the Student Registration page, leading to a Reflected Cross-Site Scripting issue
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Analysis
by VulDB Data Team • 11/27/2021
The vulnerability identified as CVE-2021-24873 affects the Tutor LMS WordPress plugin version 1.9.10 and earlier, representing a critical security flaw that undermines the integrity of user input handling within the plugin's student registration functionality. This issue resides in the plugin's failure to properly sanitise and escape user-supplied data before rendering it back in HTML attributes on the student registration page, creating a pathway for malicious actors to inject arbitrary JavaScript code. The vulnerability specifically targets the plugin's student registration component, which is a core feature for educational platforms leveraging the Tutor LMS system.
The technical implementation of this flaw stems from improper input validation and output escaping mechanisms within the plugin's codebase. When users submit data through the student registration form, the plugin processes this information without adequate sanitisation before incorporating it into HTML attributes such as input fields, hidden elements, or other form components. This oversight allows attackers to craft malicious payloads that, when executed, can be reflected back to other users browsing the registration page. The vulnerability manifests as a reflected cross-site scripting attack, where the malicious script is executed in the victim's browser context when they interact with the affected page.
The operational impact of this vulnerability extends beyond simple data integrity concerns, as it provides attackers with the capability to execute arbitrary JavaScript code within the context of authenticated users' browsers. This could enable session hijacking, credential theft, redirection to malicious sites, or the execution of additional attacks against the WordPress platform or connected systems. The reflected nature of the vulnerability means that attackers can exploit it through crafted URLs or form submissions, making it particularly dangerous for educational institutions that rely on the Tutor LMS plugin for student management. The vulnerability affects any user who interacts with the student registration functionality, including both administrators and regular users who might be tricked into clicking malicious links.
This vulnerability aligns with CWE-79, which specifically addresses Cross-Site Scripting flaws in software applications, and maps to ATT&CK technique T1566.001 for the initial compromise through spearphishing with a link. The improper sanitisation of user input creates a persistent security risk that can be exploited by threat actors to gain unauthorized access to sensitive educational data. Organizations using Tutor LMS plugin versions prior to 1.9.11 face significant exposure to these risks, particularly in environments where the plugin handles sensitive student information. The vulnerability demonstrates a fundamental lack of secure coding practices and highlights the importance of implementing proper input validation and output escaping mechanisms in web applications. Security teams should prioritize immediate remediation through plugin updates, while also implementing additional monitoring and defensive measures to detect potential exploitation attempts. The vulnerability underscores the critical need for regular security assessments and adherence to secure coding standards, particularly in educational platforms that handle sensitive user data and require robust security controls to protect against increasingly sophisticated cyber threats.