CVE-2025-52900 is a medium-severity (CVSS 5.5) Incorrect Default Permissions vulnerability in github.com/filebrowser/filebrowser/v2. A fix is available for github.com/filebrowser/filebrowser/v2 — see the affected versions and patch details below.
File Browser has Insecure File Permissions
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2025-52900.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
github.com/filebrowser/filebrowser/v2🐹github.com/filebrowser/filebrowserReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Summary
The file access permissions for files uploaded to or created from File Browser are never explicitly set by the application. The same is true for the database used by File Browser. On standard servers where the umask configuration has not been hardened before, this makes all the stated files readable by any operating system account.
Impact
The default permissions for new files on a standard Linux system are 0644, making them world-readable.
That means that at least the following parties have full read access to all files managed by the Filebrowser from all scopes, as well as its database (including the password hashes stored in there):
- All OS accounts on the server
- All other applications running on the same server
- Any Filebrowser user with Command Execution privileges having access to a command that allows reading a file's content
Vulnerability Description
On a Linux system, the file access permissions of new files are designated by the system wide umask setting, unless they are configured manually.
Most distributions set this value to 022 by default which gives every account on the system read permissions on the file.
$ umask
022
$ touch foo
$ ls -l foo
-rw-r--r-- 1 sba sba 0 31. Mär 15:08 foo
Proof of Concept
Upload or create a file in the Filebrowser GUI and list the directory contents from a shell:
$ ls -l /srv/filebrowser/testdir
total 12
-rw-r--r-- 1 sba sba 7703 Mar 25 16:07 dummy1.pdf
-rw-r--r-- 1 sba sba 3 Mar 25 15:46 testfile.txt
The same can be validated for Docker based deployments within the container:
$ docker exec -it e0f075082a2c ls /srv/testdir -l
total 12
-rw-r--r-- 1 1000 1000 7703 Mar 25 15:07 dummy1.pdf
-rw-r--r-- 1 1000 1000 3 Mar 25 14:46 testfile.txt
Furthermore, the database used by the Filebrowser application is readable by any account:
$ ls -l /srv/filebrowser/filebrowser.db
-rw-rw-r-- 1 sba sba 65536 Mar 25 09:58 /srv/filebrowser/filebrowser.db
Recommended Countermeasures
Since the system's umask configuration cannot be controlled by the Filebrowser, the application needs to set the permissions of all new files manually upon creation. No permissions should be given to the other category.
Implementing this won't fix the permissions for active instances after an update, so site administrators will need to fix the permissions manually:
$ chmod o-rwx -R /srv/filebrowser/datadir
Timeline
2025-03-25Identified the vulnerability in version 2.32.02025-04-11Contacted the project2025-04-18Vulnerability disclosed to the project2025-06-25Uploaded advisories to the project's GitHub repository2025-06-26CVE ID assigned by GitHub2025-06-26Fix released with version 2.33.7
References
- CWE-276: Incorrect Default Permissions
- What is Umask and How To Setup Default umask Under Linux?
- Original Advisory
Credits
- Mathias Tausig (SBA Research)
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/filebrowser/filebrowser/v2 | all versions | 2.33.7go get github.com/filebrowser/filebrowser/v2@v2.33.7 |
| 🐹Go | github.com/filebrowser/filebrowser | all versions | No fix |
Affected Products
filebrowserfilebrowserDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/filebrowser/filebrowser/v2, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/filebrowser/filebrowser/v2 to 2.33.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-52900 is resolved across your whole dependency graph.
Workarounds
Close the privilege gap rather than the entry point: audit which accounts, roles and service identities can reach the affected operation, drop the component to the least privilege it actually needs, and review file and directory permissions created by earlier installs — a default left in place is what makes this reachable.
Frequently Asked Questions
Is CVE-2025-52900 in your dependencies?
Find it across Go, including transitive dependencies.