GHSA-ccc3-fvfx-mw3v
MobSF Path Traversal in GET /download/<filename> using absolute filenames
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
mobsfReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Summary
The GET /download/<filename> route uses string path verification via os.path.commonprefix, which allows an authenticated user to download files outside the DWD_DIR download directory from "neighboring" directories whose absolute paths begin with the same prefix as DWD_DIR (e.g., .../downloads_bak, .../downloads.old). This is a Directory Traversal (escape) leading to a data leak.
Details
def is_safe_path(safe_root, check_path):
safe_root = os.path.realpath(os.path.normpath(safe_root))
check_path = os.path.realpath(os.path.normpath(check_path))
return os.path.commonprefix([check_path, safe_root]) == safe_root
commonprefix compares raw strings, not path components. For:
safe_root = /home/mobsf/.MobSF/downloads
check_path = /home/mobsf/.MobSF/downloads_bak/test.txt
the function returns True, incorrectly treating downloads_bak as inside downloads. Download handler:
# MobSF/views/home.py
@login_required
def download(request):
root = settings.DWD_DIR
filename = request.path.replace('/download/', '', 1)
dwd_file = Path(root) / filename # absolute 'filename' ignores 'root'
if '../' in filename or not is_safe_path(root, dwd_file):
return HttpResponseForbidden(...)
ext = dwd_file.suffix
if ext in settings.ALLOWED_EXTENSIONS and dwd_file.is_file():
return file_download(dwd_file, ...)
If the client supplies an absolute path in filename (starts with / or C:/), Path(root) / filename resolves to that absolute path; the flawed is_safe_path then accepts any sibling directory whose absolute path shares the same string prefix. The ../ check does not catch this.
Which file types are retrievable: Whatever is allowed by settings.ALLOWED_EXTENSIONS
PoC
Prereqs: authenticated user; standard install. Assume:
settings.DWD_DIR = /home/mobsf/.MobSF/downloads
Prepare a sibling directory with the same string prefix and a test file:
mkdir -p /home/mobsf/.MobSF/downloads_bak
echo "test" > /home/mobsf/.MobSF/downloads_bak/test.txt
As an authenticated user, request (note the leading / in the filename and the double/triple slash after /download/ to preserve it):
GET /download///home/mobsf/.MobSF/downloads_bak/test.txt HTTP/1.1
Host: <HOST>
Cookie: sessionid=<YOUR_SESSION>
Other working sibling directory names (if present):
…/downloads.old/...
…/downloads_backup/...
…/downloads1/...
…/downloads-archive/...
…/downloads 2024/... (URL-encoded space: downloads%202024)
Impact
Any authenticated user can download files (with allowed extensions) from sibling directories whose absolute paths start with the same string prefix as DWD_DIR.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | mobsf | all versions | 4.4.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mobsf. 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 mobsf to 4.4.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-ccc3-fvfx-mw3v 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-ccc3-fvfx-mw3v 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-ccc3-fvfx-mw3v. 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-ccc3-fvfx-mw3v in your dependencies?
O3 detects GHSA-ccc3-fvfx-mw3v across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.