FileBrowser has Path Traversal in Public Share Links that Exposes Files Outside Shared DirectoryGHSA-mr74-928f-rw69
Fix: filebrowser/filebrowser@31194fbGHSA-mr74-928f-rw69 is a Information Exposure 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.
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.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for GHSA-mr74-928f-rw69.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
Real-World Exposure
github.com/filebrowser/filebrowser/v2Real-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
When a user creates a public share link for a directory, the withHashFile middleware in http/public.go (line 59) uses filepath.Dir(link.Path) to compute the BasePathFs root. This sets the filesystem root to the parent directory instead of the shared directory itself, allowing anyone with the share link to browse and download files from all sibling directories.
Details
In http/public.go lines 52-64, the withHashFile function handles public share link requests:
basePath := link.Path // e.g. "/documents/shared"
filePath := ""
if file.IsDir {
basePath = filepath.Dir(basePath) // BUG: becomes "/documents" (parent!)
filePath = ifPath
}
d.user.Fs = afero.NewBasePathFs(d.user.Fs, basePath)
When a directory at /documents/shared is shared, filepath.Dir("/documents/shared") evaluates to "/documents". The BasePathFs is then rooted at the parent directory /documents/, giving the share link access to everything under /documents/ - not just the intended /documents/shared/.
This affects both publicShareHandler (directory listing via /api/public/share/{hash}) and publicDlHandler (file download via /api/public/dl/{hash}/path).
PoC
- Set up filebrowser with a user whose scope contains:
-
/documents/shared/public-file.txt(intended to be shared)
-
/documents/secrets/passwords.txt(NOT intended to be shared)
-
/documents/private/financial.csv(NOT intended to be shared)
- Create a public share link for the directory
/documents/shared(via POST/api/share/documents/shared) - Access the share link:
GET /api/public/share/{hash} -
- Expected: Lists only contents of
/documents/shared/
- Expected: Lists only contents of
-
- Actual: Lists contents of
/documents/(parent), revealingsecrets/,private/, andshared/directories
- Actual: Lists contents of
- Download sibling files:
GET /api/public/dl/{hash}/secrets/passwords.txt -
- Expected: 404 or 403 (file outside share scope)
-
- Actual: 200 with file contents (sibling file downloaded successfully)
Standalone Go test reproducing the exact vulnerable code path with
afero.NewBasePathFs:
- Actual: 200 with file contents (sibling file downloaded successfully)
Standalone Go test reproducing the exact vulnerable code path with
func TestShareScopeEscape(t *testing.T) {
baseFs := afero.NewMemMapFs()
afero.WriteFile(baseFs, "/documents/shared/public.txt", []byte("public"), 0644)
afero.WriteFile(baseFs, "/documents/secrets/passwords.txt", []byte("admin:hunter2"), 0644)
linkPath := "/documents/shared"
basePath := filepath.Dir(linkPath) // BUG: "/documents"
scopedFs := afero.NewBasePathFs(baseFs, basePath)
// Sibling file is accessible through the share:
f, err := scopedFs.Open("/secrets/passwords.txt")
// err is nil - file accessible! Content: "admin:hunter2"
}
This test passes, confirming the vulnerability.
Impact
Unauthenticated information disclosure (CWE-200, CWE-706). Anyone with a public share link for a directory can:
- Browse all sibling directories and files of the shared directory
-
- Download any file within the parent directory scope
-
- This works without authentication (public shares) or after providing the share password (password-protected shares) All filebrowser v2.x installations that use directory sharing are affected.
Recommended Fix
Remove the filepath.Dir() call and use link.Path directly as the BasePathFs root:
if file.IsDir {
// Don't change basePath - keep it as link.Path
filePath = ifPath
}
d.user.Fs = afero.NewBasePathFs(d.user.Fs, basePath)
Affected commit: e3d00d591b567a8bfe3b02e42ba586859002c77d (latest)
File: http/public.go, line 59
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/filebrowser/filebrowser/v2 | all versions | 2.61.0go get github.com/filebrowser/filebrowser/v2@v2.61.0 |
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 2.61.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-mr74-928f-rw69 is resolved across your whole dependency graph.
Workarounds
Assume what was exposed is already known: rotate any credential, token or key that the affected component could return, restrict the endpoint to callers that genuinely need it, and strip sensitive fields from responses and error output at the boundary rather than relying on the client not to read them.
Frequently Asked Questions
Is GHSA-mr74-928f-rw69 in your dependencies?
Find it across Go, including transitive dependencies.