CVE-2016-10795 in cPanel
Summary
by MITRE
cPanel before 59.9999.145 allows stored XSS in the WHM tail_upcp2.cgi interface (SEC-156).
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 07/21/2020
The vulnerability identified as CVE-2016-10795 represents a critical stored cross-site scripting flaw within the cPanel software ecosystem, specifically affecting versions prior to 59.9999.145. This security weakness resides within the WHM tail_upcp2.cgi interface, which is a component designed to monitor and display system updates and maintenance activities. The flaw enables attackers to inject malicious scripts that persist in the application's database and execute whenever users access the affected interface, creating a persistent threat vector that can compromise multiple users over time. The vulnerability's classification as stored XSS indicates that malicious payloads are not merely reflected in responses but are permanently stored within the application's data stores, making them particularly dangerous as they can affect any user who views the compromised content without requiring additional user interaction beyond accessing the vulnerable page.
The technical implementation of this vulnerability stems from insufficient input validation and output sanitization within the tail_upcp2.cgi component of WHM. When system administrators or users access this interface to review update logs or system information, the application fails to properly sanitize user-supplied data before rendering it in the web interface. This allows attackers to submit malicious payloads through input fields or parameters that are then stored in the application's database. The stored nature of the vulnerability means that when legitimate users access the WHM interface, their browsers execute the malicious scripts within the context of their authenticated sessions, potentially enabling full administrative control over the cPanel environment. This flaw aligns with CWE-79, which specifically addresses cross-site scripting vulnerabilities, and represents a significant deviation from secure coding practices that require proper input validation and output encoding.
The operational impact of CVE-2016-10795 extends far beyond simple data corruption or display issues, as it can lead to complete system compromise when exploited by malicious actors. An attacker who successfully exploits this vulnerability can execute arbitrary code within the context of the cPanel administrator's session, potentially gaining access to sensitive system information, modifying configurations, creating new user accounts, or even executing commands on the underlying server. The vulnerability affects WHM (Web Host Manager) interfaces, which typically provide administrative access to hosting environments, making the potential attack surface particularly concerning. The stored nature of the exploit means that once a malicious payload is injected, it can affect multiple users who access the compromised interface, potentially leading to widespread system compromise across organizations that rely on cPanel for hosting management. This vulnerability directly maps to ATT&CK technique T1059.007, which covers the use of script-based commands, and T1078.004, which addresses legitimate credentials use for persistence.
Organizations affected by CVE-2016-10795 should implement immediate remediation measures including upgrading to cPanel version 59.9999.145 or later, which contains the necessary patches to address the stored XSS vulnerability. System administrators should also conduct thorough security assessments of their cPanel installations to identify any potential exploitation attempts that may have occurred before the patch was applied. Additional mitigation strategies include implementing web application firewalls to detect and block malicious payloads, conducting regular security audits of input validation mechanisms, and establishing monitoring procedures to detect unusual activity in WHM interfaces. The vulnerability highlights the importance of maintaining up-to-date software versions and implementing proper input sanitization techniques across all web applications. Security teams should also consider implementing principle of least privilege access controls for WHM interfaces and establishing regular security training for administrators to recognize potential exploitation attempts. Organizations with multiple cPanel installations should prioritize patching efforts and conduct vulnerability assessments to ensure no other systems within their infrastructure are similarly exposed to this type of persistent threat vector.