8

CVSS Score

3.1

-

CVSS Score

Basic Information

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CVE-2025-52903

CVE-2025-52903: filebrowser Allows Shell Commands to Spawn Other Commands

[!NOTE] This feature has been disabled by default for all installations from v2.33.8 onwards, including for existent installations. To exploit this vulnerability, the instance administrator must turn on a feature and ignore all the warnings about known vulnerabilities. We're publishing this new advisory to make it clear that all vulnerabilities concerning this feature are disclosed.

For more information about tracking vulnerability issues related to the Command Execution features, check https://github.com/filebrowser/filebrowser/issues/5199.

Summary

The Command Execution feature of File Browser only allows the execution of shell command which have been predefined on a user-specific allowlist. Many tools allow the execution of arbitrary different commands, rendering this limitation void.

Impact

The concrete impact depends on the commands being granted to the attacker, but the large number of standard commands allowing the execution of subcommands makes it likely that every user having the Execute commands permissions can exploit this vulnerability. Everyone who can exploit it will have full code execution rights with the uid of the server process.

Vulnerability Description

Many Linux commands allow the execution of arbitrary different commands. For example, if a user is authorized to run only the find command and nothing else, this restriction can be circumvented by using the -exec flag.

Some common commands having the ability to launch external commands and which are included in the official container image of Filebrowser are listed below. The website https://gtfobins.github.io gives a comprehensive overview:

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CVE-2025-52903

CVE-2025-52903:

8

CVSS Score

3.1

-

CVSS Score

Basic Information

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Technical Details

Package Name	Ecosystem	Vulnerable Versions	First Patched Version
github.com/filebrowser/filebrowser/v2	go	< 2.33.10	2.33.10

Technical Details

Vulnerability Intelligence
Miggo AI

Root Cause Analysis

The vulnerability exists in the command execution feature of File Browser, where the application fails to properly restrict the execution of sub-commands. The core of the issue lies in how the application parses and validates user-provided commands, especially when a shell is used for execution. The provided patch addresses this by making several key changes. First, the runner.ParseCommand function in runner/parser.go is modified to correctly separate the command from its arguments, even when a shell is used. This prevents attackers from using shell features to execute arbitrary sub-commands. Second, the commandsHandler function in http/commands.go is updated to use the new runner.ParseCommand and to perform a more robust check against the user's allowed commands. Finally, the users.User.CanExecute function is removed, and its logic is integrated directly into commandsHandler, simplifying the validation process and removing a potential point of failure. By analyzing these changes, I was able to identify the functions that were part of the vulnerable execution flow and were modified to mitigate the vulnerability.

Vulnerable functions

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Vulnerability Intelligence
Miggo AI

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WAF Protection Rules

WAF Rule

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Reasoning

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