CVE-2026-3839 in Unraid
Summary
by MITRE • 03/16/2026
Unraid Authentication Request Path Traversal Authentication Bypass Vulnerability. This vulnerability allows remote attackers to bypass authentication on affected installations of Unraid. Authentication is not required to exploit this vulnerability.
The specific flaw exists within the auth-request.php file. The issue results from the lack of proper validation of a user-supplied path prior to using it in authentications. An attacker can leverage this vulnerability to bypass authentication on the system. Was ZDI-CAN-28912.
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Analysis
by VulDB Data Team • 03/25/2026
The CVE-2026-3839 vulnerability represents a critical authentication bypass flaw in Unraid systems that operates through a path traversal mechanism in the auth-request.php component. This vulnerability falls under the category of weak input validation and improper authentication controls, making it particularly dangerous as it requires no authentication to exploit. The flaw resides in how the system processes user-supplied paths during authentication requests, creating an avenue for malicious actors to circumvent the entire authentication framework. Security researchers have identified this issue as a significant risk to Unraid installations, as it allows remote attackers to gain unauthorized access to systems without proper credentials.
The technical implementation of this vulnerability stems from insufficient validation of path parameters within the authentication request processing logic. When the auth-request.php file handles incoming authentication requests, it fails to properly sanitize or validate user-provided path data before utilizing it in the authentication flow. This lack of input validation creates a path traversal condition where an attacker can manipulate the path parameter to access restricted authentication mechanisms. The vulnerability is classified as CWE-22 Path Traversal and aligns with ATT&CK technique T1078 Valid Accounts, as it enables unauthorized access through bypassed authentication controls. The absence of proper path validation allows attackers to craft malicious requests that can traverse the file system or authentication layers, ultimately leading to system compromise.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it fundamentally undermines the security posture of affected Unraid installations. Attackers can exploit this flaw to gain full administrative privileges without presenting valid credentials, potentially leading to complete system compromise, data exfiltration, or disruption of services. The vulnerability affects all versions of Unraid that are susceptible to this path traversal mechanism, making it a widespread concern for organizations relying on this platform. Systems with Unraid installations are particularly vulnerable because the authentication bypass occurs at the core authentication layer, meaning that once exploited, the attacker can access all system functionalities, including user management, configuration changes, and potentially network access controls. This vulnerability is especially concerning in enterprise environments where Unraid systems may serve as network infrastructure components or storage solutions.
Mitigation strategies for CVE-2026-3839 should focus on immediate patching of affected systems and implementation of proper input validation controls. Organizations must ensure that all Unraid installations are updated with the latest security patches provided by the vendor, as this vulnerability requires specific fixes to address the path traversal logic in auth-request.php. Network segmentation and access controls should be implemented to limit exposure of Unraid systems to untrusted networks, while monitoring systems should be configured to detect unusual authentication patterns or path traversal attempts. The implementation of proper parameter validation, including input sanitization and path normalization, will prevent malicious path data from being processed in authentication requests. Additionally, security teams should consider implementing intrusion detection systems that can identify and alert on suspicious authentication request patterns that may indicate exploitation attempts. The vulnerability also highlights the importance of principle of least privilege in authentication systems, ensuring that even if path traversal occurs, the impact remains limited through proper access control implementations.