GHSA-mr74-928f-rw69
FileBrowser has Path Traversal in Public Share Links that Exposes Files Outside Shared Directory
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
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 | 2.61.0 |
Detection & 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. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
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
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-mr74-928f-rw69 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-mr74-928f-rw69. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-mr74-928f-rw69 in your dependencies?
O3 detects GHSA-mr74-928f-rw69 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.