CVE-2020-10113 in cPanel
Summary
by MITRE
cPanel before 84.0.20 allows self XSS via a temporary character-set specification (SEC-515).
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Analysis
by VulDB Data Team • 05/10/2025
The vulnerability identified as CVE-2020-10113 affects cPanel versions prior to 84.0.20 and represents a self-cross-site scripting flaw that exploits a temporary character-set specification mechanism. This vulnerability falls under the category of insecure input handling and improper output encoding, creating a dangerous condition where malicious actors can inject malicious scripts into the application's temporary character-set specifications. The flaw specifically targets the application's handling of character encoding parameters that are temporarily set during processing operations, allowing attackers to manipulate these specifications to execute malicious code within the context of a victim's browser session.
The technical implementation of this vulnerability occurs when cPanel processes temporary character-set specifications without adequate sanitization or validation of input parameters. When users interact with certain administrative functions or data processing operations, the application creates temporary character-set configurations that are not properly escaped or validated before being rendered in the user interface. This creates an opportunity for attackers to inject malicious JavaScript code through carefully crafted character-set parameters that are subsequently executed when the temporary configuration is processed. The vulnerability is classified as a self-XSS because it leverages the application's own mechanisms to execute malicious code rather than relying on external injection points, making it particularly dangerous as it bypasses traditional XSS protection mechanisms.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with the ability to perform actions within the context of authenticated user sessions. This could enable unauthorized access to sensitive administrative functions, data exfiltration, session hijacking, or privilege escalation within the cPanel environment. The vulnerability is particularly concerning in shared hosting environments where multiple users may be managing different accounts on the same cPanel instance, as a successful exploitation could potentially allow an attacker to gain access to other users' accounts or administrative controls. The temporary nature of the character-set specification makes this vulnerability especially difficult to detect through standard security monitoring as the malicious code execution occurs only during specific processing operations.
Security professionals should implement immediate mitigation strategies including upgrading to cPanel version 84.0.20 or later, which contains the necessary patches to address the character-set specification handling. Organizations should also review their current cPanel configurations to ensure that temporary character-set specifications are properly sanitized and that appropriate output encoding is applied to all user-supplied data. The vulnerability aligns with CWE-79 which addresses cross-site scripting flaws, and represents a specific implementation weakness in input validation and output encoding practices. From an ATT&CK perspective, this vulnerability maps to technique T1059.007 for command and script injection, and could potentially be leveraged to progress through the adversary lifecycle by enabling further privilege escalation or lateral movement within compromised environments. Organizations should also consider implementing web application firewalls and additional monitoring of character-set parameter usage within their cPanel installations to detect potential exploitation attempts.