CVE-2021-47903 in Web Server Enterprise
Summary
by MITRE • 01/23/2026
LiteSpeed Web Server Enterprise 5.4.11 contains an authenticated command injection vulnerability in the external app configuration interface. Authenticated administrators can inject shell commands through the 'Command' parameter in the server configuration, allowing remote code execution via path traversal and bash command injection.
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Analysis
by VulDB Data Team • 01/24/2026
The CVE-2021-47903 vulnerability represents a critical authenticated command injection flaw within LiteSpeed Web Server Enterprise version 5.4.11. This vulnerability exists within the external application configuration interface, specifically targeting the 'Command' parameter handling mechanism. The flaw stems from inadequate input validation and sanitization processes that fail to properly escape or filter user-supplied commands before execution. Security researchers identified that when administrators access the server configuration interface to manage external applications, the system does not sufficiently validate or sanitize the Command parameter, creating an exploitable pathway for malicious actors.
The technical exploitation of this vulnerability requires an authenticated administrative account, which significantly reduces the attack surface but does not eliminate the risk entirely. Attackers can leverage this flaw through path traversal techniques combined with bash command injection methods to execute arbitrary shell commands on the affected server. The vulnerability manifests when the application processes the Command parameter without proper sanitization, allowing attackers to inject malicious commands that get executed with the privileges of the web server process. This creates a direct pathway for remote code execution, potentially enabling attackers to gain full control over the server environment.
The operational impact of CVE-2021-47903 extends beyond simple command execution, as it can lead to complete system compromise and data exfiltration. An attacker with administrative access could leverage this vulnerability to establish persistent backdoors, escalate privileges, or deploy additional malware within the server infrastructure. The vulnerability affects enterprise environments where LiteSpeed Web Server is deployed, potentially compromising multiple websites and applications hosted on the same server. Organizations using this web server version face significant risk of data breaches, service disruption, and regulatory compliance violations due to the severity of potential exploitation. The vulnerability aligns with CWE-78, which describes improper neutralization of special elements used in OS commands, and maps to ATT&CK technique T1059.004 for command and scripting interpreter, specifically bash shell commands.
Mitigation strategies for this vulnerability involve immediate patching of the LiteSpeed Web Server to version 5.4.12 or later, which contains the necessary security fixes. Organizations should also implement network segmentation and access controls to limit administrative access to the web server configuration interface. Additional defensive measures include monitoring for unusual command execution patterns, implementing web application firewalls to detect and block malicious command injection attempts, and conducting regular security audits of web server configurations. System administrators should also review and tighten access controls, ensuring that only necessary personnel have administrative privileges to the server configuration interface. The vulnerability demonstrates the critical importance of input validation and proper sanitization in web applications, particularly those handling administrative functions and system-level commands.