File Browser’s insecure JWT handling can lead to session replay attacks after logout
Date: 2025-07
Affected: go/github.com/filebrowser/filebrowser/v2, go/github.com/filebrowser/filebrowser
Attack vector: other
Category: vulnerability-disclosure
Severity: High
CVE: CVE-2025-53826
CWE: CWE-305
CWE-384
CWE-613

### 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)


Mitigations:

Architectural layers (MAESTRO):