GHSA-r8g5-cgf2-4m4m — picklescan
Fix: mmaitre314/picklescan#53GHSA-r8g5-cgf2-4m4m is a Deserialization of Untrusted Data vulnerability in picklescan. A fix is available for picklescan — see the affected versions and patch details below.
Picklescan missing detection when calling numpy.f2py.crackfortran.getlincoef
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.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA’s SSVC triage for GHSA-r8g5-cgf2-4m4m.
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.
Real-World Exposure
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
An unsafe deserialization vulnerability allows an attacker to execute arbitrary code on the host when loading a malicious pickle payload from an untrusted source.
Details
The numpy.f2py.crackfortran module exposes many functions that call eval on arbitrary strings of values. This is the case for getlincoef and _eval_length. This list is probably not exhaustive.
According to https://numpy.org/doc/stable/reference/security.html#advice-for-using-numpy-on-untrusted-data, the whole numpy.f2py should be considered unsafe when loading a pickle.
PoC
from numpy.f2py.crackfortran import getlincoef
class EvilClass:
def __reduce__(self):
payload = "__import__('os').system('echo \"successful attack\"')"
return getlincoef, (payload, [])
Impact
Who is impacted? Any organization or individual relying on picklescan to detect malicious pickle files from untrusted sources.
What is the impact? Attackers can embed malicious code in pickle file that remains undetected but executes when the pickle file is loaded.
Supply Chain Attack: Attackers can distribute infected pickle files across ML models, APIs, or saved Python objects.
Note
The problem was originally reported to the joblib project, but this was deemed unrelated to joblib itself. However, I checked that picklescan was indeed vulnerable.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | picklescan | all versions | 0.0.33pip install --upgrade 'picklescan==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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update picklescan to 0.0.33 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-r8g5-cgf2-4m4m 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-r8g5-cgf2-4m4m can be triaged on real exposure rather than presence alone.
Tailored to GHSA-r8g5-cgf2-4m4m. 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-r8g5-cgf2-4m4m in your dependencies?
O3 Security finds GHSA-r8g5-cgf2-4m4m across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.