Rammadaeus/poc-joblib-compression-bypass

Security PoC: Joblib Compressed Pickle Scanner Bypass

WARNING: This repository contains proof-of-concept files that demonstrate a security vulnerability. The files execute benign commands (echo + id) to prove arbitrary code execution. Do not modify the payload to include harmful commands.

Vulnerability

Joblib compressed pickle files bypass both PickleScan and ModelScan security scanners while achieving arbitrary code execution via joblib.load().

All three compression algorithms (zlib, bz2, lzma) result in scanner bypass.

Files

File	Description
poc_generator.py	Generates 3 malicious compressed joblib files
reproduce.sh	One-command full reproduction
poc_joblib_bypass_zlib.joblib	zlib compressed, bypasses scanners, RCE on load
poc_joblib_bypass_bz2.joblib	bz2 compressed, bypasses scanners, RCE on load
poc_joblib_bypass_lzma.joblib	lzma compressed, bypasses scanners, RCE on load
SUBMISSION.md	Full vulnerability writeup

Reproduction

bash reproduce.sh

This will install dependencies, generate PoC files, scan with both scanners (showing clean results), and then load with joblib to demonstrate code execution.

Affected Software

• PickleScan (mmaitre314/picklescan) - reports "0 infected", exit code 0
• ModelScan (protectai/modelscan) - reports "No issues found!"

Root Cause

Both scanners use pickletools.genops() which cannot parse compressed data. Compression headers are treated as unknown opcodes, errors are caught, and files are reported as clean.

Responsible Disclosure

This PoC is part of a responsible disclosure through the Huntr MFV program. Access is gated and restricted to authorized reviewers.