CVE-2019-15107 in Webmin
Summary
by MITRE
An issue was discovered in Webmin <=1.920. The parameter old in password_change.cgi contains a command injection vulnerability.
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Analysis
by VulDB Data Team • 05/22/2026
The vulnerability identified as CVE-2019-15107 represents a critical command injection flaw within Webmin version 1.920 and earlier, exposing systems to potentially severe remote code execution risks. This vulnerability specifically affects the password_change.cgi script which handles user authentication and password modification functions. The flaw manifests through the old parameter within the password_change.cgi component, where insufficient input validation allows malicious actors to inject arbitrary commands that execute with the privileges of the Webmin service account. The vulnerability stems from improper sanitization of user-supplied input, creating an attack vector that enables unauthorized command execution on the affected system. This issue directly aligns with CWE-77 which categorizes command injection vulnerabilities as weaknesses where untrusted input is incorporated into system commands without proper validation or escaping mechanisms. The impact of this vulnerability extends beyond simple password modification as it provides attackers with elevated privileges to execute arbitrary code on the target system, potentially leading to complete system compromise.
The technical exploitation of CVE-2019-15107 occurs when an attacker submits malicious input through the old parameter in the password_change.cgi script. This parameter is designed to validate existing passwords before allowing password changes, but the lack of proper input sanitization allows attackers to append shell commands that execute during the password validation process. The vulnerability operates at the application layer and can be exploited remotely without requiring authentication for the initial command injection, though valid credentials may be necessary to fully leverage the privilege escalation potential. Attackers can leverage this vulnerability to execute system commands, access sensitive data, modify system configurations, or establish persistent access through backdoor creation. The attack vector follows the pattern described in the MITRE ATT&CK framework under T1059 for command and scripting interpreter, specifically targeting the execution of malicious commands through web application interfaces. The flaw demonstrates a classic improper input validation issue where user-controllable parameters are directly incorporated into system calls without adequate sanitization or escaping.
The operational impact of this vulnerability is significant for organizations running affected Webmin versions, as it creates a direct path to system compromise through remote exploitation. Systems exposed to the internet or internal networks without proper segmentation face immediate risk, as the vulnerability can be exploited by attackers without requiring additional privileges or complex attack chains. The vulnerability affects not only individual user accounts but potentially the entire system infrastructure, as Webmin typically operates with elevated privileges to manage system configurations and user accounts. Organizations may experience unauthorized access to sensitive system information, data exfiltration, system file manipulation, and potential establishment of persistent backdoors. The vulnerability's impact is amplified when Webmin is configured with administrative privileges, as successful exploitation can lead to complete system takeover. Security teams must consider the potential for lateral movement within networks where Webmin is deployed, as compromised systems can serve as launch points for further attacks against adjacent systems. The vulnerability also impacts compliance requirements, as unauthorized access to system management interfaces violates security policies and regulatory standards.
Mitigation strategies for CVE-2019-15107 should prioritize immediate patching of affected Webmin installations to version 1.921 or later, which includes fixes for the command injection vulnerability. Organizations should implement network segmentation to limit exposure of Webmin interfaces to trusted networks only, reducing the attack surface for remote exploitation attempts. Additional protective measures include configuring firewall rules to restrict access to Webmin ports, implementing multi-factor authentication for administrative access, and monitoring for suspicious login patterns or command execution attempts. Security professionals should conduct comprehensive vulnerability assessments to identify all instances of affected Webmin installations across their infrastructure and establish automated patch management processes to prevent similar issues in the future. The mitigation approach aligns with security best practices outlined in NIST SP 800-53 and ISO 27001 standards, particularly focusing on access control and vulnerability management controls. Regular security audits should verify that all administrative interfaces are properly secured and that input validation mechanisms are in place to prevent similar command injection vulnerabilities in other applications. Organizations should also implement intrusion detection systems to monitor for exploitation attempts targeting known vulnerabilities and establish incident response procedures to quickly address any successful exploitation attempts.