CVE-2021-24418 in Smooth Scroll Page Plugin
Summary
by MITRE • 07/13/2021
The Smooth Scroll Page Up/Down Buttons WordPress plugin through 1.4 does not properly sanitise and validate its psb_positioning settings, allowing high privilege users such as admin to set an XSS payload in it, which will be executed in all pages of the blog
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 07/15/2021
The CVE-2021-24418 vulnerability resides within the Smooth Scroll Page Up/Down Buttons WordPress plugin version 1.4 and earlier, representing a critical cross-site scripting weakness that exploits improper input validation and sanitization mechanisms. This vulnerability specifically targets the psb_positioning settings parameter, which is designed to control the positioning of scroll buttons on web pages. The flaw allows attackers with administrative privileges to inject malicious JavaScript code into the plugin's configuration settings, creating a persistent XSS vector that affects all pages within the WordPress installation. The vulnerability's severity is amplified by the fact that it requires only administrative access to exploit, making it particularly dangerous in environments where admin credentials might be compromised or where privilege escalation occurs through other attack vectors.
The technical exploitation of this vulnerability follows a classic XSS attack pattern where malicious input is not properly sanitized before being stored and subsequently executed in the user's browser context. The psb_positioning parameter accepts user-supplied input without adequate validation or sanitization, allowing attackers to inject script tags or other malicious payloads that will execute whenever the affected pages are loaded. This type of vulnerability falls under CWE-79 which specifically addresses Cross-Site Scripting flaws, and represents a variant of stored XSS where the malicious code is permanently stored on the server and executed on subsequent page requests. The vulnerability's impact extends beyond simple script execution as it can be leveraged for session hijacking, data exfiltration, or further attack escalation within the compromised WordPress environment.
The operational impact of CVE-2021-24418 is significant for WordPress administrators and security teams responsible for maintaining web application integrity. Once exploited, the vulnerability allows attackers to execute arbitrary JavaScript code in the context of any user visiting pages where the smooth scroll buttons are displayed, potentially compromising user sessions and enabling unauthorized access to sensitive data. The persistent nature of stored XSS means that the malicious payload remains active until manually removed from the plugin settings, providing attackers with extended access windows. This vulnerability can be particularly dangerous in multi-user environments where administrators might be unaware of the malicious code injection, and it aligns with ATT&CK technique T1566 which covers phishing with malicious attachments or links, as the XSS payload could be used to deliver additional malicious content or redirect users to compromised sites.
Mitigation strategies for CVE-2021-24418 should prioritize immediate plugin updates to versions that address the sanitization issues, as the vendor has likely released patches to resolve the XSS vulnerability. Security teams should implement input validation and sanitization measures at multiple layers, including application-level filtering and content security policies to prevent script execution. Regular security audits of WordPress plugins and themes are essential to identify similar vulnerabilities, while monitoring for unusual administrative activities can help detect potential exploitation attempts. The vulnerability also highlights the importance of principle of least privilege, ensuring that administrative access is carefully controlled and monitored. Additionally, implementing web application firewalls and security headers such as Content Security Policy can provide additional protection layers against XSS attacks, though these should complement rather than replace proper input validation mechanisms.