File Browser allows sensitive data to be transferred in URL
Date: 2025-06
Affected: go/github.com/filebrowser/filebrowser, go/github.com/filebrowser/filebrowser/v2
Attack vector: info-disclosure
Category: vulnerability-disclosure
Severity: Medium
CVE: CVE-2025-52901
CWE: CWE-598
CVSS: 4.5 (CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N)

## Summary URLs that are accessed by a user are commonly logged in many locations, both server- and client-side. It is thus good practice to never transmit any secret information as part of a URL. The *Filebrowser* violates this practice, since access tokens are used as GET parameters. ## Impact The *JSON Web Token (JWT)* which is used as a session identifier will get leaked to anyone having access to the URLs accessed by the user. This will give the attacker full access to the user's account and, in consequence, to all sensitive files the user has access to. ## Description Sensitive information in URLs is logged by several components (see the following examples), even if access is protected by TLS. * The browser history * The access logs on the affected web server * Proxy servers or reverse proxy servers * Third-party servers via the HTTP referrer header In case attackers can access certain logs, they could read the included sensitive data. ## Proof of Concept ## When a file is downloaded via the web interface, the JWT is part of the URL: ```http GET /api/raw/testdir/testfile.txt?auth=eyJh[...]_r4EQ HTTP/1.1 Host: filebrowser.local:8080 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:128.0) Gecko/20100101 Firefox/128.0 Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Language: en-US,en;q=0.5 Accept-Encoding: gzip, deflate, br Connection: keep-alive Referer: http://filebrowser.local:8080/files/testdir/ Cookie: auth=eyJh[...]_r4EQ Upgrade


Mitigations:

Architectural layers (MAESTRO):