1Panel is an open-source web-based control panel designed for Linux server management. Versions 2.0.14 and earlier rely on the Gin web framework's default TrustedProxies setting, which is configured as 0.0.0.0/0, effectively trusting all incoming IP addresses as proxies. This misconfiguration allows any client to spoof the X-Forwarded-For HTTP header, which is commonly used to identify the originating IP address of a client connecting through a proxy or load balancer. 1Panel uses the ClientIP() function to enforce IP-based access controls, including AllowIPs, API whitelists, and localhost-only restrictions. Because ClientIP() trusts the X-Forwarded-For header without proper validation, an attacker can send a forged header with a whitelisted IP address such as 127.0.0.1, bypassing these IP-based security checks. This results in an authentication bypass (CWE-290), enabling unauthorized users to gain access to sensitive administrative functions without credentials. The vulnerability is remotely exploitable without any authentication or user interaction, increasing its risk. Although no known exploits are currently reported in the wild, the flaw significantly undermines the integrity and confidentiality of affected systems. The issue was addressed in 1Panel version 2.0.14 by correcting the TrustedProxies configuration to restrict which IPs are trusted for proxy headers, thereby preventing spoofing of the client IP address.

For European organizations, this vulnerability poses a significant risk to the security of Linux server management infrastructure using 1Panel versions below 2.0.14. Unauthorized access to the control panel can lead to exposure of sensitive configuration data, unauthorized changes to server settings, deployment of malicious code, and potential lateral movement within the network. Since the vulnerability allows bypassing IP-based restrictions without authentication, attackers can gain administrative privileges remotely, threatening confidentiality and integrity. This could result in data breaches, service disruptions, and compliance violations under regulations such as GDPR. Organizations relying on 1Panel for critical infrastructure management may face operational risks and reputational damage if exploited. The absence of known exploits in the wild provides a window for proactive remediation, but the ease of exploitation and lack of required user interaction elevate the urgency of patching.

European organizations should immediately upgrade all instances of 1Panel to version 2.0.14 or later, where the TrustedProxies configuration is properly restricted. Until upgrades can be completed, administrators should implement network-level controls to restrict access to the 1Panel interface only to trusted IP addresses via firewalls or VPNs, reducing exposure to external attackers. Additionally, review and harden any IP-based access control lists to ensure they do not rely solely on client IP headers. Employ web application firewalls (WAFs) capable of detecting and blocking suspicious X-Forwarded-For header manipulations. Monitor access logs for anomalous IP addresses or repeated attempts to spoof headers. Consider disabling or limiting the use of proxy headers if not required in the deployment environment. Finally, conduct security awareness training for administrators to recognize and respond to potential unauthorized access attempts.