CVE-2025-53826

File Browser provides a file managing interface within a specified directory and it can be used to upload, delete, preview, rename, and edit files. In version 2.39.0, File Browser’s authentication system issues long-lived JWT tokens that remain valid even after the user logs out. As of time of publication, no known patches exist.

File Browser provides a file managing interface within a specified directory and it can be used to upload, delete, preview, rename, and edit files. In version 2.39.0, File Browser’s authentication system issues long-lived JWT tokens that remain valid even after the user logs out. As of time of publication, no known patches exist.

File Browser’s insecure JWT handling can lead to session replay attacks after logout in github.com/filebrowser/filebrowser

### Summary File Browser’s authentication system issues long-lived JWT tokens that remain valid even after the user logs out. Please refer to the CWE's listed in this report for further reference and system standards. In summary, the main issue is: - Tokens remain valid after logout (session replay attacks) In this report, I used docker as the documentation instruct: ``` docker run \ -v filebrowser_data:/srv \ -v filebrowser_database:/database \ -v filebrowser_config:/config \ -p 8080:80 \ filebrowser/filebrowser ``` ### Details **Issue: Tokens remain valid after logout (session replay attacks)** After logging in and receiving a JWT token, the user can explicitly "log out." However, this action does not invalidate the issued JWT. Any captured token can be replayed post-logout until it expires naturally. The backend does not track active sessions or invalidate existing tokens on logout. Login request: ``` POST /api/login HTTP/1.1 Host: machine.local:8090 Content-Length: 69 {"username":"admin","password":"password-here","recaptcha":""} ``` The check found in the code `https://github.com/filebrowser/filebrowser/blob/master/http/auth.go` is not enough. There is no server-side blacklist or token invalidation on logout. Token renewal and validity only depends on expiry and user store timestamps: ``` expired := !tk.VerifyExpiresAt(time.Now().Add(time.Hour), true) updated := tk.IssuedAt != nil && tk.IssuedAt.Unix() < d.store.Users.LastUpdate(tk.User.ID) ``` ### PoC **Issue: Tokens remain valid after logout (session replay attacks)** - Login and capture the generate JWT. Eg. the http request: ``` POST /api/login HTTP/1.1 Host: machine.local:8090 Content-Length: 69 {"username":"admin","password":"password-here","recaptcha":""} ``` - Logout in the dashboard. And then try to use the old generated JWT to access any authenticated endpoint eg: ``` GET /api/resources HTTP/1.1 Host: machine.local:8090 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/138.0.0.0 Safari/537.36 X-Auth: Old-JWT-token-here Content-Length: 173 Accept: */* Referer: http://machine.local:8090/files/ Accept-Encoding: gzip, deflate, br Accept-Language: en-US,en;q=0.9 Content-Length: 26 Connection: keep-alive ``` ### Impact - A valid JWT remains active after user logout. - If stolen, tokens persist access indefinitely until expiry. - Violates OWASP Top 10 A2:2021 - Broken Authentication. ### Recommendations - Read all CWE's attached in this report - Invalidate JWTs on logout via session store / token blacklist. - Reduce JWT ExpiresAt where possible or use short-lived + refresh tokens.

File Browser proporciona una interfaz de gestión de archivos dentro de un directorio específico y permite cargar, eliminar, previsualizar, renombrar y editar archivos. En la versión 2.39.0, el sistema de autenticación del Explorador de Archivos emite tokens JWT de larga duración que siguen siendo válidos incluso después de cerrar la sesión. Al momento de la publicación, no se conocían parches.