File Browser Authorization and Path Traversal

Authorization bypass in File Browser allows unauthenticated access to shared files after permissions revoked. When administrators revoke a user's Share and Download permissions in File Browser (versions prior to 2.63.1), previously created share links remain accessible to unauthenticated users due to missing permission re-validation in the public share handler. This CWE-863 authorization flaw enables persistent unauthorized data access with high confidentiality impact (CVSS 8.2), though no public exploit or active exploitation (not in CISA KEV) has been identified at time of analysis.

Auto-provisioned users in File Browser's proxy authentication flow inherit elevated execution permissions that were explicitly blocked in the self-registration flow, enabling unauthorized command execution. Versions prior to 2.63.1 grant execute capabilities to proxy-auth users from global defaults, bypassing security controls added in commit b6a4fb1. This affects File Browser instances using proxy authentication for automatic user provisioning. No public exploit identified at time of analysis, though EPSS probability warrants attention given the network-accessible attack surface and high confidentiality/integrity impact.

Remote code execution in File Browser versions 2.0.0 through 2.63.1 allows authenticated administrators to execute arbitrary OS commands via malicious filenames. The vulnerability stems from unsanitized variable substitution in the hook system, which processes file events (upload, rename, delete) using administrator-defined shell commands. Attackers with file write permissions can inject shell metacharacters into filenames that trigger command execution when hooks fire. No public exploit identified at time of analysis, though EPSS data not provided. The vulnerable feature has been disabled by default from v2.33.8 onwards as a mitigation measure.

File Browser versions prior to 2.63.1 contain a path traversal vulnerability in the Matches() function that fails to enforce directory boundaries when evaluating access control rules. An attacker can bypass intended access restrictions by exploiting the use of strings.HasPrefix() without trailing directory separators, allowing a rule intended to restrict access to /uploads to inadvertently grant or deny access to similarly-named directories such as /uploads_backup/. This affects all File Browser versions before 2.63.1 and requires network access but no authentication or user interaction; no public exploit code or active exploitation has been confirmed at time of analysis.

File Browser versions prior to 2.63.1 allow authenticated users with download permission disabled to bypass access controls and read arbitrary text file content through the resourceGetHandler endpoint in http/resource.go, which fails to validate the Perm.Download permission flag unlike three other content-serving endpoints that correctly enforce this check. This authentication bypass affects any File Browser deployment where users are granted access but restricted from downloading files, and is fixed in version 2.63.1.