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How the mentioned CVE works (around 20 lines):
The vulnerability exploits a gap in the Picklescan security tool’s detection capabilities. Picklescan scans pickle files for known dangerous functions but fails to recognize `numpy.f2py.crackfortran.param_eval` as one. Attackers craft a malicious pickle file where the `__reduce__` method returns a call to this `param_eval` function. The `param_eval` function, designed to evaluate Fortran parameter expressions, can be misused to evaluate and execute arbitrary Python code strings. When the `__reduce__` method is called during deserialization, it executes `param_eval` with attacker-controlled arguments, such as a string like os.system('ls'). This leads to the execution of arbitrary system commands. The victim, after scanning the file with Picklescan and receiving no warnings, may proceed to load the file using pickle.load(), triggering the remote code execution. The core issue is that the attacker’s payload resides in a function not on Picklescan’s blocklist, allowing it to bypass security checks undetected.
DailyCVE Form:
Platform: Picklescan/Python Ecosystem
Version: Not Specified
Vulnerability: Code Execution
Severity: Critical
Date: 2025-12-30
Prediction: 2026-02-15
What Undercode Say:
Analytics:
`pip show picklescan`
`python -m picklescan -h`
`python -m picklescan –path ./model.pkl`
`python3 exploit_generate.py`
`cat malicious.pkl | xxd | head -20`
Bash commands and codes related to the blog
python3 -c "import pickle, numpy; data = pickle.dumps(RCE()); print('Payload created')"
class RCE:
def <strong>reduce</strong>(self):
from numpy.f2py.crackfortran import param_eval
return (param_eval, ("os.system('id')", None, None, None))
How Exploit:
Attackers embed malicious `__reduce__` method in a pickle file. The method calls numpy.f2py.crackfortran.param_eval. The function evaluates a string containing system commands. The malicious file bypasses Picklescan detection. The file is distributed within ML model repositories. Victims load the model using pickle.load(). The `__reduce__` method executes automatically. Arbitrary code runs on the victim’s system.
Protection from this CVE:
Update Picklescan library.
Avoid unpickling untrusted data.
Use safer serialization formats.
Monitor for tool patches.
Sandbox pickle loading.
Impact:
Remote Code Execution.
ML Pipeline Compromise.
Supply Chain Attack.
Undetected Malware Distribution.
System Takeover.
🎯Let’s Practice Exploiting & Learn Patching For Free:
Sources:
Reported By: github.com
Extra Source Hub:
Undercode
