CVE-2021-24326 in All 404 Redirect to Homepage Plugin
Summary
by MITRE • 05/17/2021
The tab parameter of the settings page of the All 404 Redirect to Homepage WordPress plugin before 1.21 was vulnerable to an authenticated reflected Cross-Site Scripting (XSS) issue as user input was not properly sanitised before being output in an attribute.
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Analysis
by VulDB Data Team • 05/22/2021
The vulnerability identified as CVE-2021-24326 affects the All 404 Redirect to Homepage WordPress plugin, specifically targeting versions prior to 1.21. This issue represents a critical security flaw that enables authenticated attackers to execute malicious scripts within the context of a victim's browser through a reflected cross-site scripting vector. The vulnerability manifests in the plugin's settings page where the tab parameter fails to undergo proper input sanitization before being rendered in an HTML attribute, creating an exploitable condition that directly violates web application security best practices.
The technical flaw resides in the improper handling of user-supplied input within the plugin's administrative interface. When an authenticated user navigates to the settings page and manipulates the tab parameter, the plugin fails to sanitize this input before incorporating it into HTML attributes. This reflects a classic XSS vulnerability pattern where malicious payloads can be injected and subsequently executed when the affected page is rendered. The vulnerability specifically targets the tab parameter which is processed without adequate validation or encoding, allowing attackers to inject malicious JavaScript code that gets executed in the browser context of authenticated users.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with potential access to sensitive administrative functions and data within the WordPress environment. An authenticated attacker with access to the plugin settings can craft malicious URLs containing reflected XSS payloads that, when visited by other administrators or privileged users, would execute the injected code. This could lead to session hijacking, privilege escalation, or the complete compromise of the WordPress installation. The vulnerability demonstrates a failure in input validation and output encoding practices that aligns with CWE-79, which specifically addresses cross-site scripting flaws in web applications.
Mitigation strategies for this vulnerability should prioritize immediate plugin updates to version 1.21 or later where the sanitization issue has been addressed. Administrators should also implement additional security measures including regular security audits, input validation enforcement, and monitoring of administrative interfaces for suspicious activity. The remediation process must include proper output encoding of all user-supplied parameters before rendering them in HTML attributes, following the principle of least privilege and defense in depth. Organizations should also consider implementing web application firewalls and security headers to provide additional layers of protection against similar vulnerabilities. This case exemplifies the importance of proper input sanitization and output encoding practices as outlined in the OWASP Top Ten and ATT&CK framework's defensive strategies for web application security.