CVE-2018-20928 in cPanel
Summary
by MITRE
cPanel before 70.0.23 allows stored XSS via the cpaddons vendor interface (SEC-391).
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Analysis
by VulDB Data Team • 07/18/2020
The vulnerability identified as CVE-2018-20928 represents a critical stored cross-site scripting flaw within the cPanel web-based control panel system. This vulnerability affects versions prior to 70.0.23 and specifically targets the cpaddons vendor interface, which serves as a component for managing third-party add-ons and applications within the cPanel environment. The issue stems from inadequate input validation and output encoding mechanisms that fail to properly sanitize user-supplied data before rendering it within the web interface. This allows malicious actors to inject malicious scripts that persist in the system and execute against unsuspecting users who access the affected interface.
The technical exploitation of this vulnerability occurs through the manipulation of input fields within the cpaddons vendor interface where user-provided data is stored and subsequently displayed without proper sanitization. When a victim navigates to the compromised interface, the stored malicious script executes in their browser context, potentially leading to session hijacking, credential theft, or arbitrary code execution on the victim's machine. The flaw aligns with CWE-79 which categorizes cross-site scripting vulnerabilities as weaknesses in input validation and output encoding. This vulnerability particularly impacts the integrity and confidentiality of the cPanel environment, as it enables attackers to compromise the administrative interface where critical system management functions are performed.
From an operational perspective, this vulnerability poses significant risks to organizations relying on cPanel for web hosting management, as it could allow attackers to gain unauthorized access to sensitive administrative functions. The stored nature of the XSS vulnerability means that the malicious payload persists even after the initial injection, making it particularly dangerous as it can affect multiple users over extended periods. Attackers could leverage this vulnerability to escalate privileges, modify hosting configurations, or exfiltrate sensitive data from the cPanel environment. The impact extends beyond individual user sessions to potentially compromise entire hosting environments, making this vulnerability particularly concerning for shared hosting providers and managed service organizations.
The mitigation strategy for CVE-2018-20928 requires immediate deployment of the patched cPanel version 70.0.23 or later, which includes proper input validation and output encoding mechanisms to prevent the storage and execution of malicious scripts. Organizations should also implement additional security measures such as web application firewalls, regular security audits of the cpaddons interface, and monitoring for suspicious user activity within the administrative interface. The vulnerability demonstrates the importance of maintaining up-to-date software versions and implementing defense-in-depth strategies. From an ATT&CK framework perspective, this vulnerability maps to techniques involving credential access and privilege escalation through web application exploitation, highlighting the need for comprehensive security controls that address both the technical flaw and potential attacker behaviors. Organizations should also conduct security awareness training for administrators to recognize potential XSS attack vectors and maintain regular vulnerability assessment programs to identify similar weaknesses in their hosting infrastructure.