CVE-2026-54910 in FileBrowser
Summary
by MITRE • 07/20/2026
FileBrowser Quantum is a free, self-hosted, web-based file manager. Prior to version 1.4.3-beta, the `subtitlesHandler` endpoint (`GET /api/media/subtitles`) accepts two user-controlled query parameters: `path` and `name`, both of which are used in filesystem operations without sanitization, creating two independent path traversal vectors. The primary vector is the `path` parameter: it is passed directly to `idx.GetRealPath()` without calling `SanitizeUserPath()`, allowing an attacker to escape the storage root and set `parentDir` to any directory on the host. No existing anchor file is required. The secondary vector is the `name` parameter: it is joined with `parentDir` via `filepath.Join(parentDir, name)` without stripping directory components, allowing traversal relative to any resolved `parentDir`. Any authenticated user (regardless of role or permissions) can exploit either vector to read any text file readable by the server process, including `/etc/passwd`, SSH keys, database credentials, and JWT signing keys. Version 1.4.3-beta patches the issue.
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Analysis
by VulDB Data Team • 07/20/2026
The FileBrowser Quantum application presents a critical path traversal vulnerability in its media subtitles handler endpoint that affects versions prior to 1.4.3-beta. This vulnerability stems from inadequate input sanitization of two user-controlled query parameters: path and name within the GET /api/media/subtitles endpoint. The flaw creates two distinct attack vectors that collectively enable unauthorized file access across the entire host filesystem. The primary vulnerability occurs when the path parameter bypasses proper sanitization and is directly passed to idx.GetRealPath() without invoking the SanitizeUserPath() function, allowing attackers to escape the designated storage root directory and manipulate parentDir to target any directory accessible to the server process. This design flaw eliminates the need for existing anchor files typically required in such attacks, making exploitation more straightforward and accessible to all authenticated users regardless of their role or permissions level. The secondary vulnerability arises from the name parameter processing where it is concatenated with parentDir using filepath.Join(parentDir, name) without proper directory component stripping, enabling relative path traversal relative to any resolved parent directory. Both vectors operate independently and can be exploited in combination to achieve maximum impact, as demonstrated by the ability to read sensitive system files including /etc/passwd, SSH private keys, database credentials, and JWT signing keys that are accessible to the server process.
The technical implementation of this vulnerability aligns with CWE-23 (Relative Path Traversal) and CWE-73 (Path Traversal) categories, representing a classic case of insufficient input validation combined with improper path handling. The attack surface extends beyond simple file reading to include potential credential theft and system compromise, as attackers can access files containing authentication secrets and cryptographic keys that could facilitate further attacks. From an operational perspective, this vulnerability represents a severe privilege escalation risk since any authenticated user can leverage these vectors without requiring elevated permissions or specific roles within the application. The implications extend to compliance and data protection requirements, as unauthorized access to system files containing sensitive information violates standard security practices and could result in significant regulatory consequences. The vulnerability's exploitation requires minimal technical skill and no specialized tools beyond basic HTTP request construction, making it particularly dangerous in environments where user access controls may not be properly enforced.
The remediation implemented in version 1.4.3-beta addresses both path traversal vectors through proper input sanitization and validation mechanisms. The fix ensures that the path parameter undergoes appropriate sanitization before being processed by idx.GetRealPath() and that the name parameter is properly validated to prevent directory traversal when joined with parentDir. Organizations using FileBrowser Quantum should immediately upgrade to version 1.4.3-beta or later to mitigate this vulnerability, as the attack vectors remain active in all prior versions. Security teams should also implement monitoring for suspicious API access patterns targeting system files and consider additional access controls beyond authentication to limit potential exploitation. The vulnerability demonstrates the critical importance of input validation and proper path handling in web applications, particularly in self-hosted tools that may be deployed in environments with varying security postures and threat landscapes. This issue serves as a reminder of the necessity for comprehensive security testing and validation of file system operations, especially in applications that handle user-supplied paths or filenames without adequate sanitization controls.