GHSA-6556-fwc2-fg2p
Picklescan is vulnerable to RCE through missing detection when calling numpy.f2py.crackfortran._eval_length
Blast Radius
picklescanReal-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
Picklescan uses the numpy.f2py.crackfortran._eval_length function (a NumPy F2PY helper) to execute arbitrary Python code during unpickling.
Details
Picklescan fails to detect a malicious pickle that uses the gadget numpy.f2py.crackfortran._eval_length in __reduce__, allowing arbitrary command execution when the pickle is loaded. A crafted object returns this function plus attacker‑controlled arguments; the scan reports the file as safe, but pickle.load() triggers execution.
PoC
class PoC:
def __reduce__(self):
from numpy.f2py.crackfortran import _eval_length
return _eval_length, ("__import__('os').system('whoami')", None)
Impact
- Arbitrary code execution on the victim machine once they load the “scanned as safe” pickle / model file.
- Affects any workflow relying on Picklescan to vet untrusted pickle / PyTorch artifacts.
- Enables supply‑chain poisoning of shared model files.
Credits
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | picklescan | all versions | 0.0.33 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for picklescan. 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 picklescan to 0.0.33 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-6556-fwc2-fg2p 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-6556-fwc2-fg2p 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-6556-fwc2-fg2p. 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-6556-fwc2-fg2p in your dependencies?
O3 detects GHSA-6556-fwc2-fg2p across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.