CVE-2026-119653 in Nging
Summary
by MITRE • 10/30/2026
Nging through 5.3.5 contains an information disclosure vulnerability that allows any authenticated backend user to list host directories by abusing the public-tagged /user/autocomplete_path endpoint. Low-privileged users without file-manager permission can supply arbitrary paths in the query parameter to enumerate directories readable by the Nging process and confirm specific files exist.
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Analysis
by VulDB Data Team • 10/30/2026
The vulnerability identified within Nginx through version 5.3.5 represents a critical information disclosure flaw rooted in improper access control mechanisms associated with the /user/autocomplete_path endpoint. This issue specifically affects authenticated backend users who possess low-level privileges, particularly those lacking explicit file-manager permissions. The core technical failure lies in the application's handling of query parameters within this specific API route, which fails to adequately restrict or validate the paths provided by the client against the user’s actual authorization scope. By exploiting this logic error, an attacker can supply arbitrary directory paths as input values for the autocomplete functionality intended to assist with file selection.
From a technical perspective, the vulnerability allows for path traversal and enumeration beyond the confines of the user's designated workspace. The application processes these supplied paths without sufficient sanitization or permission checks relative to the authenticated session's rights. Consequently, even users who are explicitly denied access to certain areas of the filesystem can leverage this endpoint to probe the underlying server structure. This capability enables the systematic listing of host directories that are readable by the Nginx process itself, effectively bypassing intended security boundaries designed to isolate user data and restrict administrative functions from lower-privileged accounts.
The operational impact of this vulnerability is significant as it facilitates unauthorized reconnaissance against the hosting infrastructure. An attacker can use this method to map out the directory structure of the server, identifying sensitive configuration files, backup directories, or other resources that should remain hidden from standard users. This information gathering phase is often a precursor to more severe attacks, such as local file inclusion or remote code execution if combined with other vulnerabilities in the application stack. The ability to confirm the existence of specific files further aids an attacker in tailoring subsequent exploits based on the precise software versions and configurations present on the target system.
This flaw aligns closely with CWE-200, which categorizes information exposure through error messages or unintended data leakage, as well as CWE-732, concerning improper permission assignment for critical resources. In terms of offensive security frameworks, this vulnerability maps to ATT&CK technique T1083, File and Directory Discovery, where adversaries explore the file system to gather intelligence necessary for lateral movement or privilege escalation. The exploitation relies on authenticated access, placing it within the context of post-exploitation activities where an attacker has already compromised a low-privileged account but seeks to expand their reach across the environment.
Mitigation strategies must focus on enforcing strict authorization checks at the API level rather than relying solely on frontend restrictions or general application logic. Developers should implement explicit permission validation for every request directed to the /user/autocomplete_path endpoint, ensuring that only users with specific file-manager roles can execute path enumeration operations. Additionally, input sanitization is critical; all supplied paths must be canonicalized and verified against a whitelist of allowed directories associated with the authenticated user's profile. Implementing robust access control lists for backend services will prevent low-privileged accounts from interacting with system-level resources regardless of their ability to authenticate successfully.
Regular security audits and penetration testing should include specific scenarios targeting autocomplete endpoints and file management APIs to detect similar logic flaws before they can be exploited in production environments. Monitoring logs for unusual patterns of path traversal attempts or excessive directory listing requests can also provide early detection indicators for this type of activity. By tightening the permissions model and validating inputs against a strict allowlist, organizations can effectively neutralize the risk posed by this information disclosure vulnerability and maintain the integrity of their server infrastructure.