CVE-2020-10114 in cPanel
Summary
by MITRE
cPanel before 84.0.20 allows stored self-XSS via the HTML file editor (SEC-535).
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Analysis
by VulDB Data Team • 05/10/2025
The vulnerability CVE-2020-10114 represents a stored cross-site scripting flaw in cPanel versions prior to 84.0.20, specifically within the HTML file editor component. This issue falls under the category of persistent XSS attacks where malicious code can be injected and stored within the application's file system, subsequently executed whenever users access the affected files. The vulnerability stems from inadequate input validation and output encoding mechanisms within the HTML editor interface, allowing attackers to inject malicious scripts that persist across user sessions.
The technical implementation of this vulnerability occurs through the HTML file editor's failure to properly sanitize user input before storing it in the server's file system. When administrators or users create or modify HTML files through the cPanel interface, the application does not adequately filter or escape special characters that could be interpreted as executable script code. This weakness enables attackers to embed malicious JavaScript code within HTML files that will execute in the context of other users' browsers when they view these files through the cPanel interface or when the files are served by the web server. The stored nature of this vulnerability means that the malicious payload remains active even after the initial injection, making it particularly dangerous for environments where multiple users access the same files.
The operational impact of CVE-2020-10114 extends beyond simple script execution, as it can enable attackers to perform a wide range of malicious activities including session hijacking, credential theft, and privilege escalation. An attacker who successfully exploits this vulnerability can potentially steal administrative credentials, manipulate file contents, redirect users to malicious sites, or even establish persistent backdoors within the compromised cPanel environment. The vulnerability is particularly concerning in shared hosting environments where multiple customers share the same cPanel instance, as a single compromised account could affect the entire hosting environment. This weakness directly violates security principles outlined in CWE-79, which addresses cross-site scripting vulnerabilities, and aligns with ATT&CK technique T1059.007 for scripting languages, specifically targeting the execution of malicious code through web interfaces.
Organizations affected by this vulnerability should prioritize immediate remediation through cPanel version 84.0.20 or later, which includes proper input validation and output encoding mechanisms. Additional mitigations include implementing strict input filtering at multiple layers, enabling Content Security Policy headers, and conducting regular security audits of web applications. Security teams should also consider implementing web application firewalls to detect and block suspicious script injection attempts, while monitoring for unauthorized file modifications in cPanel environments. The vulnerability demonstrates the critical importance of proper input sanitization in web applications and highlights the need for continuous security updates in hosting environments where multiple users interact with shared resources.